Drug Monograph
Regular Insulin (Human)
insulin human regular (rDNA origin) — Humulin R, Novolin R
Pharmacokinetic Profile
Half-Life
~1.5 h SC; ~20 min IV
Onset (SC / IV)
30 min SC; 10–15 min IV
Peak (SC)
2–4 hours
Duration (SC / IV)
6–8 h SC; ~4 h IV
Bioavailability (SC)
48–89%
Vd (IV)
0.32–0.67 L/kg
Clinical Information
Drug Class
Short-acting human insulin
Available Forms
U-100: 10 mL vial; U-500: 20 mL vial, 3 mL KwikPen
Route
SC and IV (U-100 only for IV)
Renal Adjustment
Reduce dose; monitor closely
Hepatic Adjustment
Reduce dose; monitor closely
Pregnancy
Compatible (human insulin)
Lactation
Compatible; adjust dose
Schedule
Prescription (U-100 Rx; ReliOn Novolin R available without Rx at Walmart)
Generic Available
Yes (biosimilar human insulin)
Indications for Regular Insulin
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Type 1 diabetes mellitus | Adults and pediatric patients | Prandial component of basal-bolus regimen (with intermediate- or long-acting insulin) | FDA Approved |
| Type 2 diabetes mellitus | Adults and pediatric patients | Prandial insulin; may be combined with basal insulin and/or oral agents | FDA Approved |
Regular insulin is the only human insulin that can be administered both subcutaneously and intravenously. While largely superseded by rapid-acting analogues (lispro, aspart, glulisine) for prandial coverage in outpatient settings, regular insulin retains critical roles in the acute care setting for diabetic ketoacidosis (DKA), hyperosmolar hyperglycaemic state (HHS), perioperative glycaemic management, and emergency treatment of hyperkalaemia. Its lower cost relative to analogues also makes it an important option where affordability drives prescribing decisions.
Off-Label Uses
Diabetic ketoacidosis (DKA) and hyperosmolar hyperglycaemic state (HHS): Continuous IV infusion of regular insulin is the standard of care for DKA and HHS. The ADA and Endocrine Society guidelines recommend IV regular insulin at 0.1–0.14 units/kg/h. (Evidence quality: High)
Emergency treatment of hyperkalaemia: IV regular insulin (10 units) co-administered with 25 g dextrose drives potassium intracellularly, providing a temporary reduction in serum potassium within 15–30 minutes. (Evidence quality: High)
Inpatient glycaemic management (IV infusion): Used as a continuous IV insulin infusion in ICU settings for critically ill patients requiring tight glucose control. (Evidence quality: High)
Gestational diabetes mellitus: Regular insulin may serve as a prandial insulin option in pregnancy. Human insulin does not cross the placenta. (Evidence quality: Moderate)
Regular Insulin Dosing
Subcutaneous Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| T1DM — prandial coverage in basal-bolus regimen | ~50% of TDD as prandial, divided across meals | Adjust by 1–2 units based on pre-meal and 2-h postprandial BG | Individualised | Inject SC ~30 minutes before meals; pair with NPH or long-acting basal TDD typically 0.4–1.0 units/kg/day (ADA 2025) |
| T2DM — prandial insulin add-on when basal alone is insufficient | 4–5 units or 10% of basal dose before the largest meal | Titrate by 1–2 units q3–7d to 2-h postprandial target | Individualised | Start with one meal, then add additional mealtime doses as needed (stepwise intensification) Consider switching to rapid-acting analogue if timing flexibility is needed |
| Inpatient SC correction scale (supplemental / sliding scale) | 2–4 units for BG 150–200 mg/dL (protocol-dependent) | Scale-based; add 50% of prior day’s correction to scheduled dose | Per protocol | Correction-only regimens are inferior to basal-bolus; use as supplement to scheduled doses Endocrine Society: avoid sliding scale as sole therapy in non-ICU patients |
| Gestational diabetes — prandial coverage for postprandial hyperglycaemia | 2–4 units before the offending meal | Titrate q2–3d to 1-h postprandial BG <140 mg/dL or 2-h <120 mg/dL | Individualised; requirements increase across trimesters | Administer 30 min before meals; reduce immediately postpartum May pair with bedtime NPH for fasting glucose control |
| U-500 regular insulin — severe insulin resistance (>200 units/day) | Convert from current TDD; divide into 2–3 doses | Titrate by 10–20% q3–7d to glycaemic targets | Individualised (may exceed 300–500+ units/day) | Use ONLY U-500 syringe or KwikPen; never mix with other insulins FDA-approved only for patients needing >200 units/day |
Intravenous Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| DKA — continuous IV infusion (adults) | 0.14 units/kg/h (no bolus) OR 0.1 units/kg bolus then 0.1 units/kg/h | Titrate to reduce BG by 50–70 mg/dL per hour | Double rate if BG does not fall 50–70 mg/dL in first hour | Reduce to 0.02–0.05 units/kg/h when BG reaches 200–250 mg/dL; add dextrose to IV fluids Do not stop infusion until anion gap closes and SC insulin is given with 2-h overlap |
| HHS — continuous IV infusion (adults) | 0.14 units/kg/h (no bolus) OR 0.1 units/kg bolus then 0.1 units/kg/h | Titrate to reduce BG by 50–70 mg/dL per hour | Individualised | Aggressive fluid resuscitation is the first priority; insulin may be started once K+ ≥3.3 mEq/L Monitor serum osmolality; aim for gradual correction to avoid cerebral oedema |
| Hyperkalaemia — emergency IV bolus | 10 units IV push | Single dose; repeat as clinically indicated | 10 units per dose | Co-administer with 25 g dextrose (50 mL D50W) to prevent hypoglycaemia Onset of K+ lowering: 15–30 min; duration: 4–6 h; monitor BG q1h for 4–6 h |
| ICU glycaemic management — continuous IV infusion | 0.5–2 units/h (or per institutional protocol) | Titrate to BG target 140–180 mg/dL (ADA 2025) | Per protocol | Monitor BG q1–2h; use 0.9% NaCl as infusion vehicle (0.1–1 unit/mL) Transition to SC basal-bolus with 2-h overlap before stopping IV infusion |
Clinical Pearl: IV-to-SC Transition
When transitioning from an IV regular insulin infusion to subcutaneous insulin, give the first dose of SC basal insulin (NPH, glargine, or degludec) at least 2 hours before discontinuing the IV infusion to prevent rebound hyperglycaemia. The IV half-life of regular insulin is only ~20 minutes (FDA PI), so glucose levels will rise rapidly if there is a gap in coverage. Calculate the estimated SC TDD from the stable hourly IV rate (multiply by 24, then reduce by 20–30% for the transition).
Renal and Hepatic Impairment
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Renal impairment (eGFR <60 mL/min) | Reduce by 25% | Titrate cautiously | Individualised | Decreased renal insulin clearance prolongs action; hypoglycaemia risk rises substantially with CKD stages 4–5 |
| Hepatic impairment | Reduce by 25–50% | Titrate cautiously | Individualised | Reduced hepatic gluconeogenesis and insulin degradation; increased hypoglycaemia risk |
Pharmacology of Regular Insulin
Mechanism of Action
Regular insulin is a soluble, unmodified recombinant human insulin identical in primary structure to endogenous insulin (molecular weight 5808 Da). In solution at therapeutic concentrations, regular insulin self-associates into hexamers stabilised by zinc ions. After subcutaneous injection, these hexamers must dissociate into dimers and monomers before absorption into the bloodstream can occur, accounting for the 30–60 minute delay in onset. Once in the circulation, insulin binds to the alpha subunits of the insulin receptor tyrosine kinase on target cell membranes, triggering autophosphorylation of the beta subunits and activation of the PI3K-Akt and Ras-MAPK signalling cascades. The principal metabolic effects include translocation of GLUT4 transporters to the cell surface in skeletal muscle and adipose tissue (promoting glucose uptake), suppression of hepatic glucose production through inhibition of glycogenolysis and gluconeogenesis, stimulation of glycogen synthesis, inhibition of lipolysis, and promotion of protein synthesis. When administered intravenously, hexamer dissociation is bypassed and the onset of action is nearly immediate (10–15 minutes).
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | SC onset ~30 min (range 10–75 min); Tmax ~2 h (range 20 min–6 h); bioavailability 48–89% (FDA PI). IV onset 10–15 min. | Must inject 30 min before meals for optimal postprandial control. Abdominal injection gives fastest absorption. Larger doses delay peak and prolong duration. |
| Distribution | Vd 0.32–0.67 L/kg (IV dosing); distributes into extracellular fluid; does not cross placenta. | Safe in pregnancy. Low Vd reflects rapid receptor-mediated uptake by target tissues. |
| Metabolism | Degraded by insulin-degrading enzyme (IDE) predominantly in liver (~60%) and kidney (~35–40%), with minor contributions from muscle and adipose tissue. | Hepatic or renal impairment reduces clearance and prolongs glucose-lowering effect; dose reductions required. |
| Elimination | SC t½ ~1.5 h (range 40 min–7 h); IV t½ ~20 min (0.1 units/kg dose). SC duration ~6–8 h; IV duration ~4 h (range 2–6 h) (FDA PI). | Short IV half-life mandates continuous infusion for sustained effect. SC duration of 6–8 h can cause late postprandial hypoglycaemia—a key disadvantage versus rapid-acting analogues. |
Side Effects of Regular Insulin
≥10%
Very Common
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Hypoglycaemia (all grades) | Most common ADR of all insulins; frequency is dose- and regimen-dependent | Risk is highest 2–4 hours post-SC injection during peak effect; rate is higher with regular insulin than rapid-acting analogues due to longer tail of activity |
| Injection site reactions (pain, erythema, pruritus) | 10–20% | Usually mild and transient; related to metacresol preservative or injection technique; site rotation reduces occurrence |
| Weight gain | ~1–4 kg in first year of insulin therapy | Insulin is anabolic; concurrent metformin or GLP-1 RA may attenuate weight gain |
1–10%
Common
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Lipodystrophy (lipoatrophy or lipohypertrophy) | 2–5% | Injection site rotation is essential; lipohypertrophy causes erratic absorption and poor glycaemic control |
| Peripheral oedema | 1–5% | Transient insulin oedema, especially with initiation or dose intensification; sodium retention mediated |
| Visual disturbances (transient refraction changes) | 1–3% | Occurs with rapid glycaemic improvement; defer new spectacle prescriptions for 6–8 weeks after starting insulin |
| Pruritus and rash | 1–3% | May be localised or generalised; if persistent, assess for true insulin allergy (rare) |
Serious
Serious (Regardless of Frequency)
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Severe hypoglycaemia (seizure, loss of consciousness) | 1–5% of patients per year | 2–4 h post-SC injection; any time during IV infusion | Glucagon IM/SC/intranasal or IV dextrose; reassess regimen; monitor BG q15 min until stable |
| Severe hypokalaemia | Uncommon (higher risk with IV infusion) | Within 30–60 min of IV administration | Monitor K+ before and during insulin infusions; replace K+ if <3.3 mEq/L before starting insulin; hold insulin until K+ ≥3.3 |
| Anaphylaxis / severe generalised allergy | Very rare (<0.01%) | Minutes to hours | Discontinue permanently; treat with epinephrine; desensitisation protocol may be considered if insulin-dependent |
| Localised cutaneous amyloidosis | Rare | Months to years with repeated same-site injection | Change injection site; monitor for erratic glucose due to unpredictable absorption |
| Transient worsening of diabetic retinopathy | Uncommon | Weeks to months after rapid HbA1c reduction | Baseline retinal exam before insulin initiation; gradual glycaemic improvement preferred |
| Heart failure exacerbation (with concurrent TZD) | Uncommon | Weeks to months | Monitor for fluid retention; reduce or stop TZD if HF signs develop |
Discontinuation
Discontinuation / Switch Rates
Outpatient SC Use
Common switch
Key driver: The 30-minute pre-meal requirement and longer duration (with late postprandial hypo risk) lead most patients and clinicians to prefer rapid-acting analogues when cost allows.
Inpatient IV Use
Protocol-driven cessation
Transition: IV insulin is discontinued after DKA/HHS resolution or ICU discharge, typically with a planned 2-hour SC overlap before stopping the drip.
| Reason for Switch | Incidence | Context |
|---|---|---|
| Timing inconvenience (30-min pre-meal) | Most common outpatient reason | Rapid-acting analogues allow injection immediately before or even after starting a meal |
| Late postprandial hypoglycaemia | Common | Regular insulin’s 6–8 h tail effect overlaps with the next meal period; analogues with 3–5 h duration reduce this risk |
| Medication error risk (U-500 concentration) | Rare but serious | U-500 dosing errors can cause 5-fold overdose if measured in a U-100 syringe; mandatory use of U-500 syringe or KwikPen |
Managing Hypoglycaemia with Regular Insulin
Due to its longer duration of action compared to rapid-acting analogues, hypoglycaemia from regular insulin may be more prolonged and may recur. Treat mild episodes with 15–20 g fast-acting carbohydrate (rule of 15). For severe episodes, administer glucagon or IV dextrose. After treatment, a sustaining snack with complex carbohydrate and protein is particularly important because the glucose-lowering tail of regular insulin extends well beyond the acute hypo episode.
Drug Interactions with Regular Insulin
Regular insulin is not metabolised through cytochrome P450 pathways. All clinically significant interactions are pharmacodynamic, involving drugs that alter glucose metabolism, insulin sensitivity, or mask hypoglycaemia symptoms. The interaction profile is shared across all insulin products.
Major
Pramlintide
MechanismAdditive glucose-lowering via delayed gastric emptying and glucagon suppression
EffectMarkedly increased hypoglycaemia risk; must not be mixed in same syringe
ManagementReduce mealtime insulin dose by 50% when initiating pramlintide; administer separately
FDA PI
Major
Thiazolidinediones (pioglitazone)
MechanismAdditive glucose-lowering and TZD-induced fluid retention
EffectHeart failure risk, peripheral oedema, hypoglycaemia
ManagementMonitor for HF signs; consider insulin or TZD dose reduction; discontinue TZD if HF develops
FDA PI
Moderate
Beta-blockers (non-selective)
MechanismMask adrenergic symptoms of hypoglycaemia; may impair counter-regulatory glucose response
EffectDelayed recognition and prolonged hypoglycaemia
ManagementPrefer cardioselective agents (metoprolol, bisoprolol); educate on non-adrenergic hypo symptoms
FDA PI
Moderate
Corticosteroids (systemic)
MechanismIncrease hepatic gluconeogenesis and peripheral insulin resistance
EffectHyperglycaemia; substantial insulin dose increases often required
ManagementIncrease monitoring; adjust insulin upward during steroid courses; taper insulin with steroid
Lexicomp
Moderate
ACE Inhibitors / ARBs
MechanismMay enhance insulin sensitivity via improved tissue blood flow
EffectPossible increased hypoglycaemia risk
ManagementMonitor BG when initiating; insulin dose reduction may be needed
Medscape
Moderate
Sulfonylureas / SGLT2 Inhibitors
MechanismAdditive glucose-lowering through independent mechanisms
EffectIncreased hypoglycaemia risk; SGLT2i may contribute to euglycaemic DKA in T1DM
ManagementReduce insulin dose by 10–20% when adding; monitor glucose frequently
FDA PI
Moderate
Alcohol (ethanol)
MechanismInhibits hepatic gluconeogenesis; unpredictable glycaemic effect
EffectIncreased risk of delayed, prolonged hypoglycaemia
ManagementAdvise eating with alcohol; increase monitoring; symptoms may mimic intoxication
FDA PI
Minor
High-dose Salicylates (≥3 g/day)
MechanismSalicylates may enhance peripheral glucose uptake and reduce hepatic glucose production
EffectPossible increased hypoglycaemia risk at anti-inflammatory doses
ManagementMonitor glucose when initiating high-dose aspirin therapy; standard analgesic doses rarely clinically significant
MedscapeMonitoring for Regular Insulin
-
Blood Glucose
Before meals and 2 h post-meal (SC); q1–2h (IV)
Routine Pre-meal and 2-hour postprandial targets guide SC prandial dose adjustments. During IV infusions (DKA, ICU), hourly BG monitoring is mandatory. CGM is recommended for T1DM and insulin-treated T2DM (ADA 2025). -
HbA1c
Every 3 months until stable, then every 6 months
Routine Target <7% for most non-pregnant adults (ADA). Individualise: <6.5% for select patients without hypo risk; <8% for elderly or limited life expectancy. -
Serum Potassium
Before and during IV insulin; periodically with SC
Trigger-based Critical during DKA management and hyperkalaemia treatment. Hold IV insulin if K+ <3.3 mEq/L until repleted. In hyperkalaemia treatment, recheck K+ at 1, 2, 4, and 6 hours. -
Renal Function
Baseline, then annually
Routine Reduced renal insulin clearance prolongs action. Check creatinine, eGFR, and urine albumin-to-creatinine ratio annually. Dose reductions needed with CKD progression. -
Injection Sites
Every visit
Routine Examine for lipodystrophy and localised cutaneous amyloidosis. These cause erratic absorption and poor glycaemic control. -
Body Weight
Every visit
Routine Insulin promotes weight gain. If progressive, reassess dietary plan and consider adjunctive therapies (metformin, GLP-1 RA). -
Anion Gap & Bicarbonate
Q2–4h during DKA management
Trigger-based Monitor until DKA resolution criteria met: pH >7.3, bicarbonate ≥15 mEq/L, anion gap ≤12, BG <200–250 mg/dL. Do not stop IV insulin until these are met and SC insulin has been administered. -
Retinal Examination
Baseline, then annually
Routine Rapid glycaemic improvement can transiently worsen diabetic retinopathy. Baseline assessment before insulin initiation; closer follow-up if pre-existing retinopathy.
Contraindications & Cautions
Absolute Contraindications
- During episodes of hypoglycaemia — do not administer insulin when blood glucose is low
- Known hypersensitivity to insulin human regular or any excipient (metacresol, glycerin)
Relative Contraindications (Specialist Input Recommended)
- Hypokalaemia (K+ <3.3 mEq/L) — insulin drives potassium intracellularly and can precipitate life-threatening arrhythmias; replete potassium before starting insulin in DKA/HHS
- Impaired hypoglycaemia awareness with recurrent severe hypoglycaemia — the 6–8 h tail effect of regular insulin heightens risk compared to rapid-acting analogues; consider switching to lispro/aspart
Use with Caution
- Renal impairment — reduced insulin clearance; dose reductions and increased monitoring required (FDA PI)
- Hepatic impairment — reduced gluconeogenesis and insulin degradation; start low, titrate slowly
- Elderly patients — conservative dosing to avoid hypoglycaemia, which may present atypically (FDA PI)
- Concurrent thiazolidinedione use — may precipitate or worsen heart failure through fluid retention
- U-500 concentration — extreme care required to prevent dosing errors; use only U-500 syringe or KwikPen; never mix with other insulins
FDA Class-Wide Safety Advisory — All Insulins
Hypoglycaemia, Medication Errors, and U-500 Safety
Accidental mix-ups between insulin products and concentrations have been reported. Regular insulin is a clear, colourless solution and must be distinguished from cloudy NPH insulin. U-500 regular insulin is five times more concentrated than U-100 and must ONLY be measured with a U-500 syringe or administered via the U-500 KwikPen. Using a U-100 syringe with U-500 insulin results in a 5-fold overdose and can be fatal. Never administer U-500 intravenously. Never share pens, needles, or syringes between patients.
Patient Counselling
Purpose of Therapy
Regular insulin is a short-acting insulin used to control blood sugar around mealtimes. In type 1 diabetes, it is always used alongside a longer-acting basal insulin. In type 2 diabetes, it may be added when basal insulin alone is no longer sufficient. In hospital, regular insulin may be given intravenously to manage very high blood sugar or life-threatening conditions like DKA.
How to Take
When injecting subcutaneously, regular insulin should be injected approximately 30 minutes before a meal. It is a clear, colourless solution — never use it if it appears cloudy, discoloured, or contains particles. Rotate injection sites within the same body region (abdomen, thigh, upper arm, buttock). Regular insulin (U-100) may be mixed with Humulin N in the same syringe: always draw the clear regular insulin first, then the cloudy NPH. Inject immediately after mixing. Do not mix regular insulin with any insulin other than Humulin N.
Low Blood Sugar (Hypoglycaemia)
Tell patientSymptoms include shakiness, sweating, fast heartbeat, dizziness, hunger, confusion, and irritability. Always carry a rapid-acting glucose source. Regular insulin peaks 2–4 hours after injection but continues working for 6–8 hours, so late hypoglycaemia is possible even several hours after the meal. Treat mild episodes with 15 g of fast-acting carbohydrate and recheck in 15 minutes. Follow up with a sustaining snack.
Call prescriberIf experiencing frequent or severe low blood sugar episodes; if losing consciousness or having seizures; if blood sugar remains low despite treatment.
Meal Timing
Tell patientRegular insulin must be injected 30 minutes before eating. If you inject and then do not eat within 30–45 minutes, blood sugar can drop dangerously low. Plan your meals so that food is ready before you inject. If a meal is unexpectedly delayed, consume a small carbohydrate snack to bridge the gap.
Call prescriberIf meal timing is consistently difficult; a switch to a rapid-acting insulin analogue (which can be injected immediately before or after eating) may be discussed.
Appearance and Mixing
Tell patientRegular insulin should always look clear and colourless. Do not use if it appears cloudy, thickened, or has particles. When mixing with NPH insulin, draw the clear regular insulin first. Never mix regular insulin with any other insulin besides Humulin N. Give the injection immediately after mixing.
Call prescriberIf the insulin looks abnormal; if uncertain about mixing technique.
Storage & Handling
Tell patientStore unopened vials in the refrigerator (2–8 °C / 36–46 °F). Once opened, Humulin R vials may be kept at room temperature (up to 30 °C / 86 °F) for up to 31 days. Novolin R vials may be kept at room temperature (up to 25 °C / 77 °F) for up to 42 days. Do not freeze; do not expose to direct heat or sunlight. Discard after the applicable in-use period even if insulin remains.
Call prescriberIf insulin has been frozen or exposed to extreme heat; if unsure whether insulin is still effective.
Sick Day Rules
Tell patientNever stop insulin during illness, even if unable to eat normally. Illness typically raises blood glucose. Check blood glucose more frequently (every 2–4 hours). Stay hydrated with clear fluids containing carbohydrates if not eating. The dose may need adjustment based on glucose readings and food intake.
Call prescriberIf blood glucose remains persistently above 250 mg/dL; if ketones are present; if unable to keep fluids down; if feeling increasingly unwell.
U-500 Safety (if prescribed)
Tell patientU-500 regular insulin is five times more concentrated than standard U-100 insulin. Always use the U-500 KwikPen or a U-500 syringe as provided. Never use a standard U-100 syringe to measure U-500 insulin—this can result in a severe, potentially fatal overdose. Never mix U-500 with any other insulin.
Call prescriberIf accidentally using the wrong syringe; if experiencing symptoms of severe low blood sugar after injection.
Sources
Regulatory (PI / SmPC)
- Eli Lilly and Company. Humulin R (insulin human injection) U-100 — Full Prescribing Information. Revised 2022. https://pi.lilly.com/us/humulin-r-pi.pdf Primary US prescribing reference for Humulin R U-100; source for PK parameters, indications, dosing, contraindications, and adverse reactions.
- Eli Lilly and Company. Humulin R U-500 (insulin human injection) — Full Prescribing Information. Revised 2024. https://pi.lilly.com/us/humulin-r-u500-pi.pdf PI for concentrated regular insulin; covers U-500 specific dosing, syringe requirements, and medication error prevention.
- DailyMed. Humulin R — insulin human injection, solution. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b519bd83-038c-4ec5-a231-a51ec5cc291f NLM-hosted structured label used to cross-verify dosing, storage, and IV administration instructions.
Guidelines
- American Diabetes Association Professional Practice Committee. 9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes — 2025. Diabetes Care. 2025;48(Suppl 1):S181–S218. https://doi.org/10.2337/dc25-S009 ADA guideline covering insulin therapy options including regular insulin; provides glycaemic targets and dosing principles for type 1 and type 2 diabetes.
- Umpierrez GE, Hellman R, Korytkowski MT, et al. Management of Hyperglycemia in Hospitalized Patients in Non-Critical Care Setting: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2012;97(1):16–38. https://doi.org/10.1210/jc.2011-2098 Guideline supporting basal-bolus regimens over sliding-scale-only insulin in non-ICU inpatients; source for correction dose protocols.
- Kitabchi AE, Umpierrez GE, Miles JM, Fisher JN. Hyperglycemic crises in adult patients with diabetes. Diabetes Care. 2009;32(7):1335–1343. https://doi.org/10.2337/dc09-9032 ADA consensus statement on DKA and HHS management; establishes IV regular insulin infusion protocols (0.14 units/kg/h or 0.1 units/kg bolus + 0.1 units/kg/h).
Key Clinical Trials
- Lipska KJ, Parker MM, Moffet HH, Huang ES, Karter AJ. Association of initiation of basal insulin analogs vs neutral protamine Hagedorn insulin with hypoglycemia-related emergency department visits or hospital admissions and with glycemic control in patients with type 2 diabetes. JAMA. 2018;320(1):53–62. https://doi.org/10.1001/jama.2018.7993 Large Kaiser Permanente cohort study demonstrating no clinically significant difference in outcomes between human insulin and analogue initiators in T2DM.
- Umpierrez GE, Smiley D, Zisman A, et al. Randomized study of basal-bolus insulin therapy in the inpatient management of patients with type 2 diabetes (RABBIT 2 Trial). Diabetes Care. 2007;30(9):2181–2186. https://doi.org/10.2337/dc07-0295 Landmark RCT demonstrating superiority of basal-bolus insulin (including regular insulin) over sliding-scale-only regimens in hospitalised T2DM patients.
- Siebenhofer A, Plank J, Berghold A, et al. Short acting insulin analogues versus regular human insulin in patients with diabetes mellitus. Cochrane Database Syst Rev. 2006;(2):CD003287. https://doi.org/10.1002/14651858.CD003287.pub4 Cochrane review comparing rapid-acting analogues with regular insulin; found small HbA1c benefit and reduced severe hypoglycaemia with analogues.
Mechanistic / Basic Science
- De Meyts P. Insulin and its receptor: structure, function, and evolution. Bioessays. 2004;26(12):1351–1362. https://doi.org/10.1002/bies.20151 Comprehensive review of insulin receptor structure and signalling, providing context for understanding the mechanism of all insulin preparations.
- Brange J, Langkjaer L. Insulin structure and stability. Pharm Biotechnol. 1993;5:315–350. https://doi.org/10.1007/978-1-4899-1236-7_11 Foundational work on insulin hexamer-to-monomer dissociation kinetics, explaining the delayed SC onset of regular insulin versus rapid-acting analogues.
Pharmacokinetics / Special Populations
- Heinemann L. Variability of insulin absorption and insulin action. Diabetes Technol Ther. 2002;4(5):673–682. https://doi.org/10.1089/152091502320798312 Characterises intra- and inter-individual variability in SC insulin absorption, including impact of injection site, dose size, and exercise on regular insulin PK.
- Rave K, Heise T, Pfützner A, et al. Impact of diabetic nephropathy on pharmacodynamic and pharmacokinetic properties of insulin in type 1 diabetic patients. Diabetes Care. 2001;24(5):886–890. https://doi.org/10.2337/diacare.24.5.886 Demonstrates prolonged insulin action and increased hypoglycaemia risk in patients with declining renal function.
- Mudaliar SR, Lindberg FA, Joyce M, et al. Insulin aspart (B28 asp-insulin): A fast-acting analog of human insulin. Diabetes Care. 1999;22(9):1501–1506. https://doi.org/10.2337/diacare.22.9.1501 Provides head-to-head PK comparison of regular insulin versus insulin aspart, contextualising the clinical advantages of rapid-acting analogues.