The 5 Types of Insulin
| Type | Examples | Onset | Peak | Duration |
|---|---|---|---|---|
| Rapid-acting | NovoRapid, Humalog, Apidra | 10–15 min | 1–2 hours | 3–5 hours |
| Short-acting (soluble) | Actrapid, Humulin S | 30–60 min | 2–4 hours | 6–8 hours |
| Intermediate-acting | Insulatard, Humulin I | 1–3 hours | 4–8 hours | 12–18 hours |
| Long-acting (basal) | Lantus, Levemir, Tresiba | 1–2 hours | Flat / none | 20–42 hours |
| Mixed | NovoMix 30, Humulin M3 | 15–30 min | 1–4 hours | 12–18 hours |
Basal-Bolus Regimen (Type 1 Diabetes)
The most physiological insulin regimen mimics the body's natural insulin secretion:
- Basal insulin (once or twice daily): Provides background insulin — e.g. Lantus at bedtime
- Bolus insulin (with each meal): Rapid-acting insulin to cover carbohydrate content — e.g. NovoRapid with each meal
- Correction doses: Extra bolus to bring high blood sugar back to target
Hypoglycaemia RiskThe most dangerous side effect of insulin is hypoglycaemia (low blood sugar). Know the signs: shaking, sweating, confusion, rapid heartbeat. Treat with 15 g fast-acting carbohydrate (3–4 glucose tablets or a small glass of juice). Always carry glucose.
Injection Sites and Rotation
| Site | Absorption Speed | Best For |
|---|---|---|
| Abdomen | Fastest | Rapid-acting insulin (meal boluses) |
| Outer thigh | Medium | Long-acting basal insulin |
| Outer upper arm | Medium | Can be used for both |
| Buttock | Slowest | Long-acting, least variation |
Lipohypertrophy WarningAlways rotate injection sites. Injecting repeatedly in the same spot causes fat to build up (lipohypertrophy) — this slows insulin absorption and makes blood sugar control unpredictable.
Should I take rapid insulin before or after food?
Rapid-acting insulin should normally be taken immediately before a meal (10–15 minutes before for Humalog/NovoRapid). Some people take it after eating if they're unsure how much they'll eat — discuss with your diabetes team.
My blood sugar is always high in the morning — why?
Fasting morning hyperglycaemia is usually due to insufficient basal insulin, the dawn phenomenon (cortisol-driven glucose release), or post-hypoglycaemia rebound. Review your long-acting dose with your diabetes nurse.
Can insulin be taken by mouth?
No — insulin is destroyed by stomach acid. It must be injected or delivered via pump. Inhaled insulin (Afrezza) exists but is not widely available.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.