Insulins · Endocrine
Insulin aspart
rapid-acting insulin analogue · NovoRapid® · NovoLog® · Fiasp®(brand names vary by market)
Mealtime insulin that acts fast enough to be taken with the food.
Also: injection, infusion
Mechanism
A single amino-acid substitution stops the insulin hexamer holding together, so it dissociates and absorbs quickly: onset in minutes rather than the half-hour that regular insulin needs.
Indications
- Type 1 diabetes
- Type 2 diabetes with mealtime requirements
- Insulin infusion in hyperglycemic emergencies and critical care
Formulations
Dosing concepts
Timing
Given with the meal, or immediately before it. Regular human insulin needs 30 minutes' lead time; treating them as interchangeable produces a hypoglycemia before the plate arrives.
What it is titrated against
Bolus doses are titrated against the glucose two hours after that meal, and against carbohydrate intake, not against the fasting reading.
Correction versus meal dose
A correction dose treats a high reading now; a meal dose covers food about to be eaten. Conflating them is a common cause of stacking and subsequent hypoglycemia.
Concepts, not prescribing instructions. Practice numbers live in current references and local protocols.
Pharmacokinetics
- Half-life
- Effect 3 to 5 h; onset 10 to 20 min, peak 1 to 3 h
- Elimination
- plasma: Renal impairment prolongs insulin action and lowers requirements
Adverse effects
- Hypoglycemiacommon & serious
- Weight gaincommon
- Lipohypertrophycommon
- Hypokalemia at high dosesseriousInsulin drives potassium into cells, which is the basis of its use in hyperkalemia and the reason for glucose and potassium monitoring on infusions.
Contraindications & precautions
Contraindications
- Hypoglycemia at the time of administration
Precautions
- Renal or hepatic impairment
- Variable meal patterns
- Exercise, which increases the effect
Interactions
Monitoring
Post-meal capillary glucose
The number bolus doses are titrated against
Hypoglycemia, including timing relative to meals and exercise
The pattern names the cause
Potassium during intravenous infusions
It falls, and it can fall fast
Counselling points
- Take it with your meal, not long before.
- If you eat less than planned, you need less insulin. Tell us if that happens often.
- Exercise increases the effect for hours afterwards; plan for it.
- Carry fast-acting glucose at all times.
Clinical pearls
- Insulin stacking, giving a correction on top of a bolus that has not finished working, is the commonest cause of an unexplained afternoon hypoglycemia on a ward.
- In hyperkalemia, insulin with dextrose shifts potassium into cells within minutes; it removes nothing from the body, and the glucose has to be watched for hours afterwards.
References & review
- Insulin aspart product monograph (consult the current version for your market) (monograph)
- Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed. (reference-work)
Last reviewed 2026-08-16 · jurisdiction: global · drug information changes; verify against current references before practice use.