Diabetes & insulin

For inpatient hyperglycemia management and insulin drip protocols, see inpatient hyperglycemia.

Insulin

TypeGenericBrandTypical useOnsetPeakDuration
Rapid-actingInsulin aspartNovoRapidPre-meal bolus10–20 min1–3 h3–5 h
Rapid-actingInsulin lisproHumalogPre-meal bolus15–30 min1–2 h4–5 h
Short-actingRegular insulinActrapidCorrection / pre-meal / IV drip30 min2–4 h6–8 h
IntermediateNPH insulinInsulatard / Humulin NBID basal60–90 min4–6 h12–18 h
BasalInsulin glargineLantusOD basal60–120 minNo peak~24 h
Basal (ultra-long)Insulin glargine U300ToujeoLong-acting basal60–120 minNo peak> 24 h
Basal (ultra-long)Insulin degludecTresibaUltra-long basal~1 hNo peak~42 h
IV insulinRegular insulin (IV)Humulin RDKA, ICU insulin dripImmediateVariesShort
PremixedBiphasic insulin aspartNovoMix 30Premixed (basal + bolus)10–20 min1–4 hUp to 24 h
PremixedBiphasic human insulin 30/70Mixtard 30Premixed, commonly used30 min2–8 hUp to 24 h

Switching basal insulin (Lantus ↔ Toujeo ↔ Tresiba): start at ~1:1 total daily units and titrate; Toujeo (U300) often needs ~10–15% more; Tresiba is long-acting and forgiving. Twice-daily NPH to once-daily basal: start at ~80% of the total daily NPH dose.

Oral & non-insulin diabetes medications

Class (examples)Continue / holdRestart when
Biguanide: metformin (Glucophage)Hold for contrast, procedures, acute illness, or declining renal function (lactic acidosis risk)Eating, stable, renal function acceptable
Sulfonylureas: gliclazide (Diamicron), glimepiride (Amaryl)Hold if NPO or intake unpredictable (hypoglycemia risk)Once eating reliably
DPP-4 inhibitors: Januvia, Trajenta, Galvus, OnglyzaContinue if eating and stable (low hypoglycemia risk)
GLP-1 RAs: Ozempic, Victoza, TrulicityHold if acutely ill or NPO (limited inpatient data). Perioperative hold is individualisedStable and eating
SGLT2 inhibitors: Forxiga, JardianceContinue or initiate for HF if no contraindication (ADA 2026, grade A). Hold for severe illness, ketonemia/ketonuria, fasting, or surgery: stop 3 days pre-op (4 for ertugliflozin). Watch for euglycemic DKA. Not for glycemic control alone inpatientEating, stable, HF indication still applies
Thiazolidinediones: pioglitazone (Actos)Hold (fluid retention / HF risk)Outpatient, once stable
Combinations: Synjardy, Xigduo, JanumetBy component: hold SGLT2i / metformin per abovePer component
Alpha-glucosidase inhibitors: acarboseHold if NPO (ineffective without oral intake)Once eating

Correction (sliding) scale

Capillary glucoseRapid-acting insulin SC
10–14 mmol/L2 units
14–17 mmol/L4 units
17–20 mmol/L6 units
> 20 mmol/L8 units + check ketones, call senior

Subcutaneous correction scale on top of the usual regimen; a conservative scale for an insulin-sensitive adult. Reduce in frail, elderly, or CKD (hypo risk); expect higher needs with insulin resistance (obesity, high-dose steroids, large home doses); titrate to the individual. DKA/HHS or nil by mouth: IV variable-rate insulin infusion (VRIII) per local protocol, not this SC scale.

Educational reference for clinicians. Doses are typical adult starting points. Cross-check allergies, interactions, current local policy, the formulary, and renal/hepatic function before prescribing.

Last updated · September 2026