Drug Monograph

Lantus, Toujeo & Biosimilars

insulin glargine
Long-Acting Basal Insulin Analog · Subcutaneous Injection · U-100 & U-300 Concentrations · Once Daily Dosing
Pharmacokinetic Profile
Onset
~3–4 hours
Peak Effect
Relatively peakless
Duration (U-100)
Up to 24 hours
Duration (U-300)
>24 hours; flatter profile
Steady State (U-300)
≥5 days
Active Metabolites
M1, M2 (B-chain cleavage)
Clinical Information
Drug Class
Long-acting human insulin analog
Lantus (U-100)
10 mL vial; 3 mL SoloStar pen
Toujeo (U-300)
SoloStar 1.5 mL (450 U); Max 3 mL (900 U)
Biosimilars
Basaglar, Semglee*, Rezvoglar*
Renal Adjustment
Monitor closely; reduce dose
Hepatic Adjustment
Monitor closely; reduce dose
Pregnancy
Acceptable; no clear adverse signal
Lactation
Compatible
Pediatric Use
Lantus: pediatric (Study D 6–15 yr); Toujeo: ≥6 yr
Schedule / Legal
Rx only (non-controlled)

*Semglee (insulin glargine-yfgn) and Rezvoglar (insulin glargine-aglr) are FDA-designated interchangeable biosimilars to Lantus. Basaglar is a follow-on/biosimilar product but is not interchangeable.

Rx

Indications

Insulin glargine is a long-acting human insulin analog produced by recombinant DNA technology in Escherichia coli (K12 strain). It differs from human insulin by a single amino acid substitution at position A21 (asparagine → glycine) and the addition of two arginines at the C-terminus of the B-chain. These modifications shift the isoelectric point such that insulin glargine is fully soluble at acidic pH (~4) but precipitates upon injection into the neutral pH of subcutaneous tissue, forming a microprecipitate from which insulin glargine is slowly released. The result is a relatively constant, peakless glucose-lowering profile over 24 hours with U-100 (Lantus, Basaglar, Semglee, Rezvoglar) and an even flatter, more prolonged profile with U-300 (Toujeo).

Lantus (insulin glargine U-100) was the first long-acting basal insulin analog approved in the United States in April 2000 (Sanofi-Aventis), and remains the most widely prescribed basal insulin globally. Toujeo (insulin glargine U-300, approved February 2015) provides three times the concentration in one-third the volume, producing a slower, more prolonged release that may reduce nocturnal hypoglycemia versus U-100 in some populations. The interchangeable biosimilars Semglee (insulin glargine-yfgn, interchangeable status July 2021) and Rezvoglar (insulin glargine-aglr, biosimilar approval December 2021; interchangeable status November 2022) provide lower-cost alternatives clinically equivalent to Lantus.

IndicationApproved PopulationTherapy TypeStatus
Diabetes mellitus — Lantus, Basaglar, Semglee, Rezvoglar (U-100)Adult and pediatric patients with diabetes mellitus (FDA pediatric efficacy data from Study D, ages 6–15 years with T1DM)Basal insulin component of basal-bolus regimen, basal-only therapy with oral antihyperglycemics in T2DM, or as monotherapyFDA Approved
Diabetes mellitus — Toujeo (U-300)Adults and pediatric patients aged ≥6 years with diabetes mellitusBasal insulin; same therapeutic role as U-100 with flatter PK profileFDA Approved
Combination with prandial / mealtime insulinsAdult and pediatric patients with T1DM or insulin-requiring T2DMMultiple daily injection (MDI) regimen with rapid-acting analogs (lispro, aspart, glulisine)FDA Approved
Combination with GLP-1 receptor agonist (fixed ratio)Adults with T2DMSoliqua 100/33 (insulin glargine + lixisenatide) provides combined basal insulin and GLP-1 RA in a single penFDA Approved
Pediatric use of Toujeo <6 yearsSafety and efficacy not establishedNot Established
Diabetic ketoacidosis (DKA)Not Recommended

Insulin glargine is not for the treatment of diabetic ketoacidosis — intravenous short-acting insulin (regular human insulin or rapid-acting analog) is required for DKA management. Within current treatment algorithms, the ADA Standards of Care position basal insulin as preferred when injectable therapy is needed in T2DM, particularly when GLP-1 receptor agonists are insufficient, contraindicated, or the patient has prominent catabolic features (significant weight loss, severe hyperglycemia, ketosis). For T1DM, basal insulin is foundational therapy. Insulin glargine has neutral cardiovascular effects in patients with prediabetes or early T2DM, established by the ORIGIN trial — it neither increases nor reduces cardiovascular events.

Off-Label and Special Population Use Notes

Inpatient hyperglycemia management (Evidence: Established off-label) — Basal insulin glargine is widely used in hospitalized non-critical patients as part of basal-bolus protocols, often replacing scheduled NPH or sliding-scale-only regimens. Endorsed by Endocrine Society inpatient guidelines despite labels not specifying inpatient use.

Gestational diabetes / pregnancy (Evidence: Acceptable based on observational data) — Insulin glargine has been used during pregnancy when needed; published studies have not reported a clear association with adverse developmental outcomes per current FDA labeling. NPH and detemir have historically been the most-studied basal insulins in pregnancy; glargine is increasingly accepted with appropriate monitoring.

Cystic fibrosis–related diabetes (CFRD) (Evidence: Acceptable off-label) — Insulin (including basal analogs) is recommended therapy; oral agents are not routinely used.

Steroid-induced hyperglycemia (Evidence: Acceptable, but NPH may be preferred for short-acting steroid coverage) — For chronic glucocorticoid-induced hyperglycemia, basal insulin glargine is reasonable. For prednisone-induced hyperglycemia following morning dosing, intermediate-acting NPH timed to peak 4–8 hours later may align better with the steroid effect.

Dose

Dosing

Insulin glargine doses are highly individualized based on metabolic needs, blood glucose monitoring, glycemic control goals, type of diabetes, prior insulin use, and concomitant antihyperglycemic therapy. All formulations are administered by subcutaneous injection only — never intravenously, intramuscularly, or via insulin pump — into the abdomen, thigh, or deltoid, with rotation of injection sites within the same region to reduce the risk of lipodystrophy and localized cutaneous amyloidosis. Dosing is once daily at any time of day, but at the same time every day. Insulin glargine must not be diluted or mixed with any other insulin or solution; doing so will alter the precipitation behavior and disrupt the prolonged absorption profile.

Available Pen and Vial Specifications

  • Lantus 10 mL multiple-dose vial — 1,000 units total; for use with U-100 syringes.
  • Lantus SoloStar prefilled pen — 3 mL (300 units); dials in 1-unit increments.
  • Toujeo SoloStar prefilled pen — 1.5 mL (450 units U-300); dials in 1-unit increments; delivers up to 80 units in a single injection.
  • Toujeo Max SoloStar prefilled pen — 3 mL (900 units U-300); dials in 2-unit increments; delivers up to 160 units in a single injection; recommended for patients requiring at least 20 units of basal insulin per day.
  • Basaglar KwikPen, Semglee pen/vial, Rezvoglar KwikPen — All U-100 (100 units/mL); 3 mL prefilled pens dial in 1-unit increments; 10 mL vial available for Semglee.
Clinical ScenarioStarting DoseTitrationTarget / MaximumNotes
T1DM — adult or pediatric, insulin-naiveApproximately ⅓ of total daily insulin requirements
U-100 or U-300, once daily SC
Adjust by 1–2 U based on FPG; monitor pre-meal and bedtime glucoseIndividualized to glycemic targetsRemaining ⅔ of TDD as rapid-acting prandial insulin distributed across meals.
T2DM — adult, insulin-naive10 units once daily or 0.2 U/kg once dailyIncrease 2 U every 3 days based on fasting plasma glucose; target FPG typically 80–130 mg/dLIndividualized; commonly 0.5–1 U/kg/day at full titrationPer FDA Lantus PI starting dose recommendation. Continue oral agents (metformin / SGLT2i / GLP-1 RA) as appropriate.
Switching from once-daily NPH insulin to Lantus / U-100 productSame total daily unit doseAdjust based on glycemic response over 1–2 weeksPer FDA Lantus PI.
Switching from twice-daily NPH insulin to Lantus / U-100 product80% of the total daily NPH dose, given as once-daily Lantus (= 20% dose reduction)Adjust over 2–4 weeksPer FDA Lantus PI Section 2.3 — applies to NPH insulin.
Switching from twice-daily NPH or detemir to Toujeo (U-300)Start at 80% of total daily NPH or detemir twice-daily dose; once dailyTitrate over 2–4 weeksPer FDA Toujeo PI.
Switching from Lantus (U-100) to Toujeo (U-300)Same unit dose initially; expect a higher Toujeo dose may be required at steady state — clinical trial patients used approximately 15% more basal insulin on ToujeoTitrate based on responsePer FDA Toujeo PI. Toujeo has lower per-unit glucose-lowering effect than Lantus due to slower release from a smaller-surface depot.
Switching from Toujeo (U-300) to Lantus / U-100 productInitial Lantus dose 80% of the Toujeo dose; once dailyTitrate based on responsePer FDA Lantus PI Section 2.3. Higher per-unit bioavailability with U-100; close glucose monitoring in week 1.
Renal impairmentNo specific algorithm in FDA label
Use lower starting dose; titrate cautiously
Slow, individualized titration; intensified glucose monitoringIndividualizedInsulin clearance is reduced in renal failure — increased risk of hypoglycemia, particularly at eGFR <30 mL/min.
Hepatic impairmentNo specific algorithm in FDA label
Use lower starting dose; titrate cautiously
Slow titration; intensified glucose monitoringIndividualizedHepatic gluconeogenesis impairment may prolong hypoglycemia.
Older adults (≥65 years)Conservative initial dose, dose increments, and maintenance dosageIndividualizedHypoglycemia may be difficult to recognize; prefer less stringent HbA1c targets (e.g., <7.5–8% per ADA).
Soliqua 100/33 (insulin glargine + lixisenatide)15 units daily (insulin-naive, on GLP-1 RA, or <30 U basal/day) or 30 units daily (currently on 30–60 U basal/day)Adjust per glycemic response60 units/day max (60 U insulin glargine + 20 mcg lixisenatide)Discontinue prior basal insulin or GLP-1 RA before initiation. T2DM only.
Missed doseIf less than ~12 hours from the missed dose, take as soon as remembered; if closer to the next dose, skip and resume regular scheduleDo not double dose. Monitor SMBG closely on day of missed dose.

Storage Conditions

  • Lantus and U-100 biosimilars (unopened): Refrigerated 36–46°F (2–8°C) until expiration date. Do not freeze.
  • Lantus 10 mL vial (in-use): 28 days at refrigerator OR room temperature (≤86°F / 30°C). Discard after 28 days regardless of remaining contents.
  • Lantus SoloStar pen (in-use): 28 days at room temperature only (≤86°F / 30°C). Do not refrigerate after first use.
  • Toujeo SoloStar and Max SoloStar pens (unopened): Refrigerated 36–46°F (2–8°C) until expiration date.
  • Toujeo SoloStar / Max SoloStar pens (in-use): 56 days at room temperature only (≤86°F / 30°C). Do not refrigerate after first use.
  • All formulations: Protect from direct heat and light. Discard if frozen.
Critical: U-100 and U-300 Are Not Interchangeable Volume-for-Volume

Toujeo U-300 contains three times the insulin concentration of Lantus U-100. Patients must be instructed to never use a syringe to withdraw insulin from a Toujeo SoloStar or Max SoloStar pen — doing so could deliver three times the intended dose, producing severe hypoglycemia. Toujeo SoloStar and Toujeo Max SoloStar pens have a “300 units/mL (U-300)” warning highlighted in honey gold on the label. The dose counter on the pen displays the number of units to be injected, requiring no recalculation. Toujeo SoloStar dials in 1-unit increments; Toujeo Max SoloStar dials in 2-unit increments — when changing between SoloStar and Max SoloStar pens, an odd-number dose should be increased or decreased by 1 unit to match the dose increments dialable on the new pen.

Choosing Between U-100 and U-300

The EDITION trial program (n >3,500 across phase 3 studies in T1DM and T2DM) demonstrated that Toujeo U-300 provides similar HbA1c reduction to Lantus U-100, with a flatter PK profile and reduced nocturnal hypoglycemia in some subpopulations. Toujeo trial patients used approximately 15% more basal insulin units than Lantus patients to achieve equivalent glycemic control, due to slower, more sustained release. Practical advantages of U-300: three times higher concentration permits one-third the injection volume, potentially relevant when daily basal doses exceed 60–80 units; longer in-use stability (56 days vs 28 days). Practical advantages of U-100: wider familiarity, more head-to-head comparator data, and significantly broader access to lower-cost interchangeable biosimilars (Semglee, Rezvoglar).

PK

Pharmacology

Mechanism of Action

Insulin glargine, like all insulins, regulates glucose metabolism by binding the insulin receptor on peripheral tissues — primarily skeletal muscle and adipose tissue — and stimulating glucose uptake while simultaneously inhibiting hepatic glucose production. Insulin also inhibits lipolysis and proteolysis and enhances protein synthesis. Insulin glargine has approximately the same receptor-level potency as endogenous human insulin; the molecular modifications affect only its pharmacokinetic profile, not its intrinsic biological activity at the insulin receptor.

The clinical innovation of insulin glargine lies in its delayed and prolonged absorption from the subcutaneous depot. At its formulation pH of approximately 4.0, insulin glargine is fully soluble. Upon subcutaneous injection, neutralization to physiologic pH causes insulin glargine to precipitate as small microcrystals. These microcrystals slowly dissolve and release insulin glargine into the circulation over 24+ hours, producing a relatively peakless basal insulin concentration. With Toujeo U-300, the higher concentration injected as a smaller volume produces a more compact subcutaneous depot with a smaller surface area, which further slows absorption — yielding an even flatter PK profile and a duration of action exceeding 24 hours at typical doses.

In humans, insulin glargine is partly metabolized at the carboxyl terminus of the B-chain in the subcutaneous depot, forming two active metabolites: M1 (21A-Gly-insulin) and M2 (21A-Gly-des-30B-Thr-insulin). These metabolites have in vitro insulin receptor binding and biological activity similar to that of human insulin. Both unchanged drug and metabolites are present in the systemic circulation.

Molecular and Formulation Characteristics

  • Chemical name: 21A-Gly-30Ba-L-Arg-30Bb-L-Arg-human insulin
  • Empirical formula: C267H404N72O78S6
  • Molecular weight: 6,063 Da
  • Formulation pH: ~4 (acidic; precipitates at neutral pH in subcutaneous tissue)
  • Lantus inactive ingredients (per mL): 30 mcg zinc, 2.7 mg m-cresol, 20 mg glycerol 85%
  • Toujeo inactive ingredients (per mL): 90 mcg zinc, 2.7 mg m-cresol, 20 mg glycerol 85%

Pharmacokinetic Profile by Formulation

ParameterLantus / U-100 BiosimilarsToujeo (U-300)
Onset of actionApproximately 3–4 hours after SC injectionSlightly later than U-100 (~6 hours)
Peak concentrationRelatively peakless; modest plateau over 12–18 hoursTmax 12 (8–14) h at 0.4 U/kg; 12 (12–18) h at 0.6 U/kg; 16 (12–20) h at 0.9 U/kg
Duration of actionUp to 24 hours>24 hours; flatter profile; serum insulin declines beyond 36 hours at higher doses
Steady stateMulti-day with once-daily dosing≥5 days of once-daily dosing (0.4–0.6 U/kg)
Intra-subject variability (CV)Lower than NPH insulin (specific value not provided in PI)21.0% at steady state (24-hour insulin exposure)
Injection site effectNo clinically relevant difference among abdomen, thigh, deltoidNo clinically relevant difference among abdomen, thigh, deltoid
Glucose-lowering effect per unit (relative)Reference (100%)Approximately 27% lower glucose-lowering per unit at 0.4 U/kg vs equivalent Lantus dose
MetabolismSubcutaneous depot cleavage at B-chain C-terminus → active metabolites M1 and M2 (similar in vitro potency to human insulin)
EliminationInsulin and metabolites cleared by receptor-mediated uptake, hepatic and renal degradation; renal impairment may modestly increase circulating insulin levels

HbA1c-Lowering Efficacy

In randomized clinical trials, insulin glargine produces clinically meaningful HbA1c reductions, the magnitude of which depends on baseline HbA1c, prior therapy, and titration intensity. In insulin-naive T2DM patients, basal insulin glargine added to oral antihyperglycemics typically produces meaningful HbA1c reductions over 6 months. In T1DM patients, glargine matches NPH insulin in HbA1c reduction while reducing nocturnal hypoglycemia in many trials. Long-term efficacy was demonstrated in the ORIGIN trial (n=12,537, median follow-up 6.2 years), where insulin glargine maintained near-normal glycemic control and reduced incident new-onset diabetes versus standard care in patients with prediabetes or early T2DM.

SE

Side Effects

Hypoglycemia is the most common and most clinically significant adverse effect of insulin glargine — as with all insulins. The long-acting profile of insulin glargine may delay recovery from hypoglycemic episodes once they occur, requiring sustained carbohydrate intake and observation. Severe hypoglycemia rates in the ORIGIN trial were 1.00 vs 0.31 per 100 patient-years (insulin glargine vs standard care). Modest weight gain (median +1.6 kg vs −0.5 kg in ORIGIN) is typical of insulin therapy generally. Other common adverse effects relate to the injection site (lipodystrophy, localized cutaneous amyloidosis, injection site pain) or are class-wide (peripheral edema, hypokalemia with overdose, immunogenicity). Serious hypersensitivity reactions are rare but can occur.

≥10% Very Common
Adverse EffectRate / PatternClinical Note
Hypoglycemia (any severity)Highly dose- and regimen-dependentThe defining adverse effect of insulin therapy; risk increases with intensified glycemic targets, missed meals, exercise, alcohol, and renal/hepatic impairment.
Anti-insulin antibodies (Toujeo, T1DM, 6-month study)79% positive at least onceIncludes 62% positive at baseline and 44% who developed antidrug antibodies during the study. No clinically significant differences in efficacy or safety attributed to antibody formation.
Anti-insulin antibodies (Toujeo, T2DM, 6-month studies)25% positive at least onceIncludes 42% positive at baseline and 20% who developed ADA during the study. Lower rate than in T1DM. No consistent clinical correlate.
Weight gainMedian +1.6 kg over 6.2 years (ORIGIN)Comparable to or slightly less than NPH in head-to-head trials.
1–10% Common
Adverse EffectApproximate IncidenceClinical Note
Severe hypoglycemia (rate, ORIGIN trial)1.00 per 100 patient-yearsVersus 0.31 per 100 PY in standard care. Defined as event requiring third-party assistance.
Injection site pain (Lantus vs NPH adult trials, FDA PI)2.7% (vs 0.7% NPH)Usually mild and self-limited; rarely leads to discontinuation. Possibly attributable to acidic pH of solution.
Lipodystrophy (lipohypertrophy and lipoatrophy)Site-rotation-dependent; typically 1–5%Reduced by rotation of injection sites within the same anatomical region.
Other injection site reactions (redness, itching, swelling, hives)~1–5%Typically mild and transient. Rotate sites; persistent reactions warrant evaluation.
Peripheral edemaVariableMore common with rapid glycemic improvement after long-standing hyperglycemia. Usually transient over weeks.
Serious Regardless of Frequency
Adverse EffectEstimated FrequencyTypical OnsetRequired Action
Severe hypoglycemia (coma, seizure, neurologic impairment)1.00/100 PY (ORIGIN)Hours; long-acting profile may delay recoveryIM/SC glucagon or IV concentrated dextrose; sustained carbohydrate intake; observe for recurrence due to long duration of action.
HypokalemiaParticularly with overdose or rapid correction of severe hyperglycemiaHoursMonitor potassium during initiation, dose changes, and DKA management. Untreated hypokalemia can cause respiratory paralysis, ventricular arrhythmia, and death.
Severe hypersensitivity / anaphylaxisRare (postmarketing)Minutes to hours after injectionDiscontinue immediately. Severe generalized allergy including anaphylaxis can be life-threatening. Re-challenge only under specialist supervision.
Localized cutaneous amyloidosis at injection sitesPostmarketing (incidence not established)Months to years of repeated injection at same siteAvoid injecting into affected areas. Insulin absorption is impaired in amyloid deposits, leading to unstable glycemia. Rotate injection sites systematically.
Heart failure exacerbation (with TZD coadministration)Class effect of TZD + insulin combinationsWeeks to monthsMonitor for signs of heart failure when insulin is combined with rosiglitazone or pioglitazone. Discontinue TZD if heart failure develops or worsens.
Medication errors / accidental insulin mix-upsReported with all insulin products; particular concern with U-300Minutes to hoursAlways check insulin labels before administration. Patients must be specifically warned never to use a syringe with Toujeo SoloStar or Max SoloStar pens.
Discontinuation Treatment Drop-Out Patterns
Common Reasons for Insulin Glargine Discontinuation
Variable in real-world practice
Top reasons: Recurrent or severe hypoglycemia; weight gain; lifestyle and adherence issues with daily injections; cost (Lantus brand) prior to biosimilar availability; switch to GLP-1 RA monotherapy or fixed-ratio combination.
Switches Between Glargine Formulations / Brands
Common cost-driven and clinically driven
Context: Cost-driven switching to interchangeable biosimilars (Semglee, Rezvoglar) is common. Clinically driven switching to Toujeo for nocturnal hypoglycemia or to a different basal analog (insulin degludec) for greater half-life or pump-compatibility considerations.
Reason for DiscontinuationPatternContext
Recurrent hypoglycemiaCommonOften resolved by dose reduction or switch to a flatter-profile basal insulin (Toujeo, degludec).
Cost / formulary changesCommonSwitching to interchangeable biosimilars (Semglee, Rezvoglar) typically clinically equivalent; switch to Basaglar requires new prescription.
Adherence / preferenceVariableSome patients with T2DM transition to GLP-1 RA monotherapy or fixed-ratio combination.
Lipohypertrophy / amyloidosisLess commonMay require switch to alternative basal insulin or careful site rotation training.
Severe hypersensitivityRareRequires permanent discontinuation; alternative basal insulin under specialist supervision.
Recognizing and Managing Severe Hypoglycemia from Insulin Glargine

Severe hypoglycemia from insulin glargine is a medical emergency. Mild episodes (intact consciousness, able to swallow): treat with 15 g of fast-acting oral carbohydrate, recheck in 15 minutes, and provide a follow-up snack containing complex carbohydrates and protein. Severe episodes (coma, seizure, inability to swallow): administer subcutaneous, intramuscular, or intranasal glucagon if available, or call emergency services for IV concentrated dextrose. Critical: because the duration of action of insulin glargine is up to 24 hours (and longer with U-300), recurrence is common after apparent recovery. Sustained carbohydrate intake and observation for at least several hours, often longer, are required. Hypokalemia must be corrected appropriately.

Int

Drug Interactions

Insulin glargine is a peptide and does not undergo CYP-mediated metabolism — it has no relevant CYP enzyme inhibition or induction potential. The clinically significant interactions are pharmacodynamic, falling into three categories per FDA Lantus PI Table 8: (1) drugs that increase the blood-glucose-lowering effect of insulin, raising hypoglycemia risk; (2) drugs that decrease the blood-glucose-lowering effect, raising hyperglycemia risk; and (3) drugs that may both increase or decrease glycemic control depending on dose, duration, and individual factors. A separate small but important category is drugs that blunt the symptoms of hypoglycemia, which do not change insulin’s effect but mask the patient’s ability to recognize hypoglycemia.

Major Other antidiabetic agents (sulfonylureas, meglitinides, GLP-1 RAs, oral antihyperglycemics)
MechanismPharmacodynamic synergy — additive glucose-lowering effect
EffectIncreased risk of hypoglycemia, particularly with sulfonylureas, meglitinides, and other insulins
ManagementWhen adding insulin glargine to a sulfonylurea or meglitinide regimen, consider reducing or discontinuing the sulfonylurea. With GLP-1 RAs, reduce basal insulin by ~10–20% at GLP-1 RA initiation in patients near goal.
FDA PI
Major Thiazolidinediones (rosiglitazone, pioglitazone)
MechanismPPAR-γ-mediated fluid retention in combination with insulin
EffectRisk of new or worsening heart failure, edema, weight gain when TZDs are combined with insulin
ManagementObserve for signs of heart failure (dyspnea, edema, weight gain). Reduce TZD dose or discontinue if heart failure develops. Use combination cautiously in patients with established heart failure.
FDA PI
Major Systemic corticosteroids (prednisone, dexamethasone, methylprednisolone)
MechanismIncreased hepatic gluconeogenesis and peripheral insulin resistance
EffectSubstantially decreased insulin effect — can produce marked hyperglycemia, particularly with high-dose or prolonged glucocorticoid use
ManagementAnticipate need for substantial insulin dose increases (often 30–50% or more) during steroid courses. Reduce dose at steroid taper to prevent hypoglycemia.
FDA PI
Major Beta-blockers (especially non-selective: propranolol, nadolol, timolol)
MechanismMask adrenergic warning symptoms of hypoglycemia (tachycardia, tremor); may blunt counter-regulatory glucagon release
EffectPatients may not recognize hypoglycemia until neuroglycopenic symptoms develop. Sweating may persist as the principal warning sign.
ManagementPrefer cardioselective beta-blockers (metoprolol, bisoprolol) when needed. Counsel patient about masked symptoms and emphasize SMBG.
FDA PI
Moderate Pentamidine
MechanismDirect beta-cell toxicity initially causing insulin release, then beta-cell destruction
EffectBiphasic — early hypoglycemia followed by hyperglycemia and (rarely) diabetes
ManagementFrequent glucose monitoring during pentamidine therapy; anticipate dose adjustments in both directions.
FDA PI
Moderate Atypical antipsychotics (olanzapine, clozapine, risperidone, quetiapine)
MechanismIncreased peripheral insulin resistance and weight gain
EffectDecreased insulin effect; need for substantially increased doses, especially with olanzapine and clozapine
ManagementIncreased monitoring, particularly when initiating or escalating antipsychotic therapy.
FDA PI
Moderate Alcohol
MechanismInhibits hepatic gluconeogenesis acutely; chronic use may impair glycemic control
EffectBidirectional — can both increase and decrease blood glucose. Severe and prolonged hypoglycemia particularly with binge drinking on an empty stomach
ManagementCounsel patients to limit alcohol and never drink on an empty stomach. Heavy drinking warrants reassessment of insulin dosing.
FDA PI
Moderate Sympathomimetic agents (albuterol, epinephrine, terbutaline)
Mechanismβ2-mediated stimulation of hepatic glucose production and glycogenolysis
EffectDecreased insulin effect; transient hyperglycemia, particularly with systemic use
ManagementInhaled bronchodilators have minimal systemic effect. Anticipate hyperglycemia during high-dose IV β-agonist therapy (e.g., asthma exacerbation).
FDA PI
Moderate ACE inhibitors / ARBs / disopyramide / fibrates / fluoxetine / MAO inhibitors / pramlintide / propoxyphene / salicylates / somatostatin analogs / sulfonamide antibiotics
MechanismVarious — increased insulin sensitivity, displacement of protein binding, or direct insulinotropic effects
EffectIncreased insulin effect; risk of hypoglycemia
ManagementIncrease SMBG when starting any of these agents; consider preemptive insulin dose reduction in patients near glycemic targets.
FDA PI
Moderate Diuretics, danazol, estrogens / oral contraceptives, glucagon, isoniazid, niacin, phenothiazines, progestogens, protease inhibitors, somatropin, thyroid hormones
MechanismVarious — increased insulin resistance, antagonism of insulin signaling, increased hepatic glucose production
EffectDecreased insulin effect; risk of hyperglycemia
ManagementIncrease SMBG when starting any of these agents; anticipate possible insulin dose increase.
FDA PI
Minor Clonidine, guanethidine, reserpine, lithium
MechanismSympatholytic effects mask catecholamine-mediated warning symptoms of hypoglycemia; clonidine and lithium can affect glucose control bidirectionally
EffectBlunted hypoglycemia awareness; bidirectional effects on glucose for clonidine and lithium
ManagementCounsel about masked hypoglycemia symptoms; encourage routine SMBG.
FDA PI
Mon

Monitoring

Monitoring of insulin glargine therapy centers on glycemic response, hypoglycemia surveillance, injection site assessment, and management of intercurrent factors that affect insulin requirements (renal/hepatic function, intercurrent medications, illness, lifestyle). Self-monitoring of blood glucose (SMBG) or continuous glucose monitoring (CGM) is foundational — particularly during initiation, titration, intercurrent illness, and changes in concomitant medications. CGM is increasingly recommended for all patients with T1DM and for many T2DM patients on multiple-daily-injection regimens.

  • HbA1c Every 3 months until at goal, then every 6 months
    Routine
    Target individualized — generally <7% for most adults; <6.5% if achievable safely without hypoglycemia; <7.5–8% for older adults, those with comorbidities, or those with a history of severe hypoglycemia.
  • Fasting Plasma Glucose (FPG) Daily during titration; periodically thereafter
    Routine
    Primary parameter for titrating basal insulin glargine. Common targets: 80–130 mg/dL (4.4–7.2 mmol/L) per ADA, with individualization for older adults and those at hypoglycemia risk.
  • Self-Monitored Blood Glucose / CGM Multiple times daily for T1DM and intensive T2DM regimens
    Routine
    CGM preferred where available. Time-in-range (TIR; 70–180 mg/dL) goal >70%. Critical during initiation, dose escalation, illness, and concomitant medication changes.
  • Hypoglycemia Symptoms Every visit; immediate review with new symptoms
    Trigger-based
    Specifically inquire about unexplained dizziness, sweating, tremor, palpitations, confusion — particularly nocturnal episodes. Beta-blocker users may lose adrenergic warning signs. Consider Gold or Clarke score for hypoglycemia awareness assessment.
  • Injection Sites At least annually; with any unexplained glycemic instability
    Trigger-based
    Inspect and palpate for lipohypertrophy, lipoatrophy, and localized cutaneous amyloidosis. Insulin absorption from such areas is impaired and erratic, often manifesting as unexplained glycemic instability.
  • Body Weight Each visit
    Routine
    Modest weight gain is typical. Significant gain may prompt review of caloric intake, addition of GLP-1 RA or SGLT2 inhibitor, or dose optimization.
  • Renal Function (eGFR) At baseline; annually thereafter (more often in CKD)
    Routine
    Worsening renal function reduces insulin clearance — increased hypoglycemia risk. Dose reduction often needed at eGFR <30 mL/min.
  • Liver Function At baseline; periodically
    Trigger-based
    Hepatic gluconeogenesis impairment increases hypoglycemia risk. Glycemic instability in advanced liver disease often requires reduced insulin doses and intensified monitoring.
  • Serum Potassium During DKA management or insulin overdose
    Trigger-based
    Insulin drives potassium intracellularly. Hypokalemia is a particular concern in DKA, with rapid correction of severe hyperglycemia, and in renal failure.
  • Lipid Panel & BP Per general CV risk management guidelines
    Routine
    Insulin glargine has neutral effects on lipoprotein profile. Standard CV risk surveillance applies.
  • Annual Diabetes Care Bundle Annually
    Routine
    Diabetic retinopathy screening, urine albumin/creatinine, foot examination, dental review, immunizations. Per ADA Standards of Care.
CI

Contraindications & Cautions

Critical Safety Warning — Concentration U-100 vs U-300: Dose Counter Use Mandatory; Never Withdraw Toujeo by Syringe

Toujeo U-300 contains three times the insulin concentration of Lantus U-100. To prevent severe hypoglycemia from inadvertent overdose, instruct patients to use only the integrated dose counter on the Toujeo SoloStar or Toujeo Max SoloStar pen — never withdraw insulin from a Toujeo pen using a syringe. Drawing 30 units from a U-300 pen using a U-100 syringe would deliver 90 units of insulin glargine. Pen labels are color-coded with “300 units/mL (U-300)” highlighted in honey gold. Toujeo SoloStar dials in 1-unit increments (max 80 units single injection); Toujeo Max SoloStar dials in 2-unit increments (max 160 units single injection).

Absolute Contraindications

  • Known hypersensitivity to insulin glargine or any excipient. Severe allergic reactions, including anaphylaxis, have occurred.
  • During an episode of hypoglycemia — do not administer insulin in a hypoglycemic patient.

Relative Contraindications / Use with Caution

  • Diabetic ketoacidosis (DKA) — insulin glargine is not appropriate primary treatment; intravenous regular insulin is required.
  • Hyperosmolar hyperglycemic state (HHS) — IV insulin is preferred initially; basal insulin glargine can be added during the transition phase to subcutaneous therapy.
  • Severe renal impairment — insulin clearance is reduced; lower starting doses and slower titration are required to prevent severe and prolonged hypoglycemia.
  • Severe hepatic impairment — diminished gluconeogenic capacity raises hypoglycemia risk. Conservative dosing and intensified monitoring required.
  • Concomitant thiazolidinedione (TZD) therapy — risk of fluid retention, edema, and heart failure exacerbation, particularly in patients with NYHA class III–IV heart failure.
  • Older adults — heightened hypoglycemia risk; conservative dosing; relaxed glycemic targets generally appropriate (HbA1c <7.5–8%).
  • Acute illness, surgery, or interrupted oral intake — insulin requirements change abruptly; doses should be adjusted with intensified monitoring or IV insulin substitution where appropriate.
  • Pregnancy — insulin glargine has been used during pregnancy; published studies have not reported a clear association with adverse developmental outcomes, though insulin detemir and NPH have historically had more pregnancy-specific data. Maternal hyperglycemia management benefits the fetus.
  • Lactation — compatible. Endogenous insulin is present in human milk and is not absorbed orally by the infant. Maternal insulin requirements may decrease postpartum during breastfeeding.
  • Visual impairment — patients who cannot read pen markings should not self-administer without assistance. Pens have audible clicks but should not be relied upon as the sole dose verification.
  • Driving and operating heavy machinery — hypoglycemia impairs concentration and reaction time. Stable glycemic control should be ensured before resuming such activities, particularly during titration.
Pt

Patient Counselling

Purpose of Therapy

Explain that insulin glargine is a long-acting “background” or “basal” insulin that works for about a full day after each injection, providing the constant low level of insulin your body needs between meals and overnight. It does not replace insulin taken with meals. The two main concerns are low blood sugar (hypoglycemia) and weight gain. Most people on insulin glargine also use a fast-acting insulin at meals (for type 1 diabetes) or oral diabetes medications like metformin, GLP-1 agonists, or SGLT2 inhibitors (for type 2 diabetes).

How to Inject

Inject once daily at the same time every day, into the subcutaneous tissue of the abdomen (avoiding the area within 2 inches of the navel), the front or outer thigh, or the back of the upper arm. Rotate injection sites within the same anatomical region to prevent lumpy or hardened areas (lipohypertrophy) that can affect insulin absorption. The insulin solution should be clear and colorless — do not use if cloudy, discolored, or contains particles.

Lantus U-100, Basaglar, Semglee, Rezvoglar: These are 100 units per mL. Standard insulin syringes (U-100) or the SoloStar/KwikPen prefilled pens can be used.

Toujeo U-300: This is three times more concentrated — 300 units per mL. Never use a syringe to withdraw insulin from a Toujeo pen. Use only the dose counter on the Toujeo SoloStar (dials in 1-unit increments, max 80 units per injection) or Toujeo Max SoloStar pen (dials in 2-unit increments, max 160 units per injection). The honey-gold “300 units/mL” label on the pen confirms the concentration.

Storage — Lantus and U-100 biosimilars: Unused pens and vials should be kept in the refrigerator (36–46°F / 2–8°C) until first use. Do not freeze. Once in use, Lantus pens are kept at room temperature (below 86°F / 30°C) and discarded after 28 days. Lantus vials in use can be kept refrigerated or at room temperature and discarded after 28 days. Storage — Toujeo: Unused pens refrigerated until first use; once in use, kept at room temperature only and discarded after 56 days. Never share insulin pens or syringes with another person, even with a new needle, due to bloodborne disease transmission risk.

Low Blood Sugar (Hypoglycemia) — The Most Important Topic
Tell patient Insulin can cause low blood sugar, particularly with missed meals, increased physical activity, alcohol, or kidney/liver problems. Symptoms include shakiness, sweating, fast heartbeat, hunger, headache, irritability, blurred vision, and confusion. Always carry a fast-acting sugar source.
Self-treat For mild symptoms: 15 g of fast-acting carbohydrate (4 oz juice, 3–4 glucose tablets, 1 tablespoon sugar/honey). Recheck in 15 minutes; repeat if still low. Follow with a snack containing protein and complex carbs. Because insulin glargine lasts about 24 hours, low blood sugar can return — keep checking your levels for several hours.
Call 911 / ER For loss of consciousness, seizure, or inability to swallow safely. A family member or caregiver should administer glucagon (auto-injector, nasal spray, or kit) if available and call emergency services.
Sick Day Rules
Tell patient Never stop insulin glargine completely during illness, even if you are not eating. Your body still needs basal insulin. If you have type 1 diabetes, stopping insulin can rapidly lead to diabetic ketoacidosis. During illness, blood sugar often runs higher despite reduced food intake.
Practical advice Check blood glucose more frequently (every 2–4 hours). Check ketones if blood glucose is >240 mg/dL or you feel unwell (T1DM). Drink fluids. Continue your basal insulin glargine; mealtime insulin may need adjustment based on intake.
Call prescriber For persistent vomiting, blood sugar above 300 mg/dL, moderate-to-large ketones, signs of dehydration, or any symptoms of DKA (rapid breathing, fruity breath, confusion).
Alcohol Use
Tell patient Alcohol can cause severe and prolonged low blood sugar, especially when consumed on an empty stomach. The risk extends well after drinking — sometimes overnight or into the next day.
Practical advice If drinking, limit to one drink for women or two drinks for men with food — never on an empty stomach. Check blood glucose before bed. Inform companions that symptoms of low blood sugar can resemble drunkenness.
Driving and Operating Machinery
Tell patient Low blood sugar impairs concentration and reaction time. Check blood glucose before driving long distances, particularly during the first weeks of therapy or after dose changes. Carry fast-acting sugar in the car. Pull over and treat low blood sugar before continuing.
Call prescriber If you experience hypoglycemia while driving — your dose may need adjustment.
Other Medications and Supplements
Tell patient Many medications affect insulin requirements. Steroids (prednisone) often raise blood sugar significantly and may require temporarily larger insulin doses. Beta-blockers may mask hypoglycemia symptoms — sweating may be the only warning sign. New oral contraceptives, thyroid medication, and antipsychotics can change insulin needs. Always inform every healthcare provider that you use insulin glargine.
Call prescriber Before starting any new prescription medication, herbal supplement, or over-the-counter product, especially during glucocorticoid courses.
Weight Changes
Tell patient Modest weight gain (about 1–3 kg over 1–2 years) is common when starting insulin. Maintaining a balanced diet, regular activity, and avoiding overcorrection of low blood sugar with excessive snacks can minimize this.
Call prescriber If significant weight gain occurs — addition of GLP-1 RA, SGLT2 inhibitor, or metformin (in T2DM) may help.
Pregnancy & Family Planning
Tell patient If you are planning pregnancy or become pregnant, contact your prescriber promptly. Insulin glargine has been used during pregnancy with no clear adverse signal, though discussion with your provider regarding alternatives is appropriate. Tight glycemic control before and during pregnancy reduces the risk of birth defects, miscarriage, and complications. Insulin requirements typically increase during the second and third trimesters.
Practical advice Continue insulin glargine while breastfeeding — it is compatible. Insulin requirements often decrease postpartum and during nursing.
Surgery & Hospitalization
Tell patient Inform anesthesiologists, surgeons, dentists, and emergency providers that you take insulin glargine and the specific product (Lantus, Toujeo, Basaglar, Semglee, or Rezvoglar). For most surgeries, your basal insulin dose is continued or reduced (often to 50–80%) the morning of the procedure to prevent intraoperative hypoglycemia, while skipping mealtime insulin if fasting.
Call prescriber Before any planned procedure or hospitalization to receive specific perioperative dosing instructions.
Switching Insulin Glargine Products
Tell patient Several different insulin glargine products are available. Lantus, Semglee, and Rezvoglar are interchangeable U-100 products and produce equivalent effects unit-for-unit. Basaglar is also U-100 but requires a new prescription (it is a biosimilar but not interchangeable). Toujeo is U-300 — three times more concentrated and requires dose adjustment when switching. Always confirm with your pharmacist that you understand which product you are receiving.
Call prescriber When the pharmacy provides a different product than what you previously used. Increased monitoring is needed during the first 1–2 weeks after any switch.
Ref

Sources

Regulatory (PI / SmPC)
  1. U.S. Food and Drug Administration. Lantus (insulin glargine) injection, for subcutaneous use. Sanofi-Aventis. Initial U.S. Approval: 2000 (NDA 21081). accessdata.fda.gov Definitive U.S. labeling for Lantus U-100 — primary source for indications, dosing (T1DM ⅓ TDD; T2DM 10 U or 0.2 U/kg starting dose; twice-daily NPH→Lantus 80% conversion; Toujeo→Lantus 80% conversion), pharmacokinetics (M1/M2 active metabolites; relatively peakless 24-hour profile), drug interactions (Table 8), Study D pediatric population (ages 6–15, T1DM, n=174 LANTUS-treated), and adverse reactions.
  2. U.S. Food and Drug Administration. Toujeo U-300 (insulin glargine) injection, for subcutaneous use. Sanofi-Aventis. Initial U.S. Approval: 2015 (NDA 206538). accessdata.fda.gov Definitive U.S. labeling for Toujeo U-300 — primary source for U-300-specific PK (Tmax 12–16 h dose-dependent, ≥5 days to steady state, 21% intra-subject variability, ~27% lower glucose-lowering per unit at 0.4 U/kg vs Lantus), conversion ratios from NPH or detemir (80%) and Lantus (same dose initially; ~15% more units typical), pediatric ≥6 yr indication, anti-insulin antibody data (T1DM 79%, T2DM 25% positive at least once), and pen specifications (SoloStar 1-U increments / 80 U max single inject; Max SoloStar 2-U increments / 160 U max single inject).
  3. U.S. Food and Drug Administration. Soliqua 100/33 (insulin glargine and lixisenatide) injection prescribing information. Sanofi-Aventis. lantus.com Reference for fixed-ratio insulin glargine + lixisenatide combination dosing (15-unit start for insulin-naive / GLP-1 RA users / <30 U basal/day; 30-unit start for 30–60 U basal/day; 60-unit/day maximum corresponding to 20 mcg lixisenatide ceiling).
  4. National Library of Medicine, DailyMed. Lantus and Toujeo full prescribing information. dailymed.nlm.nih.gov Continuously updated full prescribing information for cross-checking the most current label changes for both Lantus and Toujeo.
Key Clinical Trials & Outcomes Evidence
  1. ORIGIN Trial Investigators; Gerstein HC, Bosch J, Dagenais GR, et al. Basal insulin and cardiovascular and other outcomes in dysglycemia. N Engl J Med. 2012;367(4):319–328. doi.org/10.1056/NEJMoa1203858 · PMID 22686416 The definitive cardiovascular outcomes trial of insulin glargine: n=12,537 patients with prediabetes or early T2DM, mean age 63.5 years, median 6.2-yr follow-up. First coprimary outcome (CV death/MI/stroke) HR 1.02 (95% CI 0.94–1.11; P=0.63); second coprimary outcome (with revasc/HHF) HR 1.04 (0.97–1.11; P=0.27). Severe hypoglycemia 1.00 vs 0.31/100 PY; weight +1.6 vs −0.5 kg; new diabetes 30% vs 35% (OR 0.80; 95% CI 0.64–1.00; P=0.05); no cancer signal (HR 1.00; 0.88–1.13). Established the cardiovascular safety of insulin glargine.
  2. ORIGIN Trial Investigators; Gerstein HC, Bosch J, Dagenais GR, et al. Cardiovascular and Other Outcomes Postintervention With Insulin Glargine and Omega-3 Fatty Acids (ORIGINALE). Circulation. 2016;133(9):891–894 (presented at ADA; full data in Diabetes Care). PMID 26681720 Post-trial follow-up (additional 2.7 years) of ORIGIN — confirmed neutral cardiovascular outcomes (HR 1.01; 95% CI 0.94–1.10) and absence of cancer signal (HR 0.99; 0.88–1.12) with insulin glargine after a total of >9 years of observation.
  3. Riddle MC, Bolli GB, Ziemen M, Muehlen-Bartmer I, Bizet F, Home PD; EDITION 1 Study Investigators. New insulin glargine 300 units/mL versus glargine 100 units/mL in people with type 2 diabetes using basal and mealtime insulin: glucose control and hypoglycemia in a 6-month randomized controlled trial (EDITION 1). Diabetes Care. 2014;37(10):2755–2762. doi.org/10.2337/dc14-0991 · PMID 25078900 EDITION 1: T2DM on basal+mealtime insulin (n=807, 6 months). HbA1c reduction equivalent (LSM difference 0.00%; 95% CI −0.11 to 0.11). Nocturnal hypoglycemia lower with Gla-300 (36% vs 46%; RR 0.79; 95% CI 0.67–0.93; P<0.005). Established U-300 efficacy with reduced nocturnal hypoglycemia.
  4. Yki-Järvinen H, Bergenstal R, Ziemen M, et al; EDITION 2 Study Investigators. New insulin glargine 300 units/mL versus glargine 100 units/mL in people with type 2 diabetes using oral agents and basal insulin: glucose control and hypoglycemia in a 6-month randomized controlled trial (EDITION 2). Diabetes Care. 2014;37(12):3235–3243. doi.org/10.2337/dc14-0990 EDITION 2: T2DM on basal insulin + oral antihyperglycemic drugs. Confirmed glycemic equivalence and reduced nocturnal hypoglycemia of Gla-300 vs Gla-100 in this population.
  5. Bolli GB, Riddle MC, Bergenstal RM, et al; EDITION 3 Study Investigators. New insulin glargine 300 U/ml compared with glargine 100 U/ml in insulin-naïve people with type 2 diabetes on oral glucose-lowering drugs: a randomized controlled trial (EDITION 3). Diabetes Obes Metab. 2015;17(4):386–394. doi.org/10.1111/dom.12438 EDITION 3: Insulin-naive T2DM patients on oral glucose-lowering drugs. Demonstrated comparable HbA1c reduction with Gla-300 vs Gla-100 in this initiation population.
  6. Home PD, Bergenstal RM, Bolli GB, et al; EDITION 4 Study Investigators. New insulin glargine 300 units/mL versus glargine 100 units/mL in people with type 1 diabetes: a randomized, phase 3a, open-label clinical trial (EDITION 4). Diabetes Care. 2015;38(12):2217–2225. doi.org/10.2337/dc15-0249 EDITION 4: T1DM on basal-bolus regimen (n=549). HbA1c reduction equivalent between Gla-300 and Gla-100. Nocturnal hypoglycemia lower with Gla-300 in the first 8 weeks (RR 0.69; 95% CI 0.53–0.91); thereafter equivalent.
Biosimilars & Interchangeability
  1. U.S. Food and Drug Administration. FDA approves first interchangeable biosimilar insulin product (Semglee; insulin glargine-yfgn). July 28, 2021. fda.gov Semglee (insulin glargine-yfgn; Viatris/Biocon) — the first interchangeable biosimilar to Lantus.
  2. U.S. Food and Drug Administration. Approval of Rezvoglar (insulin glargine-aglr) as biosimilar (December 17, 2021) and as interchangeable (November 16, 2022). Rezvoglar (insulin glargine-aglr; Eli Lilly) — second interchangeable biosimilar of Lantus. Basaglar (insulin glargine; Eli Lilly), an earlier follow-on insulin glargine product approved December 2015, is a biosimilar but not designated interchangeable, so substitution at the pharmacy level requires a new prescription.
Guidelines
  1. American Diabetes Association Professional Practice Committee. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes. Diabetes Care. Updated annually. diabetesjournals.org/care Authoritative U.S. guidance on insulin initiation and titration in T1DM and T2DM, including basal-bolus and basal-plus-GLP-1 RA approaches.
  2. Davies MJ, Aroda VR, Collins BS, et al. Management of hyperglycaemia in type 2 diabetes, 2022. A consensus report by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD). Diabetes Care. 2022;45(11):2753–2786. doi.org/10.2337/dci22-0034 ADA-EASD consensus on the role of basal insulin in T2DM management, including conditions where basal insulin remains preferred (catabolic features, severe hyperglycemia, intolerance/contraindication to other agents).
  3. American Diabetes Association. Glycemic Targets: Standards of Care in Diabetes. Diabetes Care. Updated annually. Current targets for HbA1c, FPG, postprandial glucose, and CGM time-in-range.
Mechanistic / Clinical Pharmacology
  1. Becker RHA, Dahmen R, Bergmann K, Lehmann A, Jax T, Heise T. New insulin glargine 300 Units · mL−1 provides a more even activity profile and prolonged glycemic control at steady state compared with insulin glargine 100 Units · mL−1. Diabetes Care. 2015;38(4):637–643. doi.org/10.2337/dc14-0006 Pharmacodynamic and pharmacokinetic comparison of Toujeo U-300 versus Lantus U-100 — demonstrated flatter activity profile and longer duration of U-300 in euglycemic clamp studies.
  2. Yki-Järvinen H, Kauppinen-Mäkelin R, Tiikkainen M, et al. Insulin glargine or NPH combined with metformin in type 2 diabetes: the LANMET study. Diabetologia. 2006;49(3):442–451. Foundational head-to-head study of insulin glargine vs NPH in metformin-treated T2DM; established the favorable nocturnal hypoglycemia profile of glargine.