Types of Insulin

Rapid-Acting Insulin

• Examples: Insulin aspart, insulin lispro, insulin glulisine.

• Onset: ~10–20 minutes.

• Peak: 1–3 hours.

• Duration: 3–5 hours.

• Clinical use: Given before meals to control postprandial hyperglycaemia; used in basal-bolus regimens and insulin pumps.

Short-Acting Insulin

• Example: Soluble human insulin (Actrapid).

• Onset: 30–60 minutes.

• Peak: 2–4 hours.

• Duration: 6–8 hours.

• Clinical use: Pre-meal injections, correction doses in hospital.

Intermediate-Acting Insulin

• Example: Isophane insulin (NPH).

• Onset: 1–2 hours.

• Peak: 4–12 hours.

• Duration: 12–18 hours.

• Clinical use: Basal insulin in some regimens, often combined with short-acting insulin.

Long-Acting Insulin

• Examples: Insulin glargine, insulin detemir, insulin degludec.

• Onset: 1–2 hours.

• Peak: Minimal (flat profile).

• Duration: 18–42 hours (depending on product).

• Clinical use: Basal insulin for once or twice daily dosing to provide background glucose control.

Insulin Analogues

• Definition: Genetically modified human insulin to alter onset/duration (includes most rapid-acting and long-acting insulins).

• Benefits: More predictable absorption, reduced hypoglycaemia risk (especially nocturnal), flexibility with meals.

Insulin Regimens

Basal-Bolus Regimen

• Basal: Long-acting insulin once or twice daily to cover background needs.

• Bolus: Rapid- or short-acting insulin before meals.

• Benefits: Closest mimic of physiological insulin secretion; flexible with meal timing and quantity.

• Use: Standard for most people with Type 1 diabetes; also in Type 2 when required.

Continuous Subcutaneous Insulin Infusion (CSII; Insulin Pumps)

• What: Delivers rapid-acting insulin continuously via a pump and cannula.

• Basal rate: Programmed to match individual background requirements.

• Bolus doses: Given before meals via the pump.

• Benefits: Improved glycaemic control, flexibility, reduced hypoglycaemia in selected patients.

• Indications: T1D patients unable to achieve targets with multiple daily injections, recurrent hypoglycaemia, or high glycaemic variability.

Patient Education

Self-Monitoring of Blood Glucose (SMBG)

• Why: Essential for safe insulin use; allows dose adjustment and hypoglycaemia detection.

• How: Use of capillary glucose meters; frequency varies (at least 4 times/day in T1D, more if needed).

• Targets: Pre-meal 4–7 mmol/L, post-meal <9 mmol/L (individualised).

Hypoglycaemia Management

• Recognise: Symptoms include sweating, shakiness, confusion, palpitations, and in severe cases, unconsciousness.

• Treat: Fast-acting carbohydrate (e.g., 15–20 g glucose tablets or juice), repeat in 10–15 min if necessary.

• Severe cases: Glucagon injection or IV glucose if unable to swallow.

• Prevention: Education on dose adjustment with exercise, illness, and meal changes.

Insulin Storage

• Unopened insulin: Refrigerate at 2–8°C (do not freeze).

• In-use: May be kept at room temperature (below 25–30°C) for up to 28 days (check manufacturer’s advice).

• Do not expose to heat, sunlight, or freeze.

• Check expiry date before use.

Adjusting Doses in Special Populations

Elderly

• Increased risk of hypoglycaemia due to reduced renal function, irregular eating, cognitive impairment.

• Use lower starting doses, cautious titration, and long-acting analogues to minimise hypoglycaemia.

Pregnancy

• Tight glycaemic control is critical for fetal outcomes.

• Insulin requirements may increase (especially in 2nd/3rd trimesters).

• Rapid-acting and long-acting analogues (e.g., insulin lispro, aspart, detemir) are preferred; oral hypoglycaemics generally avoided.

• Frequent SMBG and dose adjustments required.

Renal Impairment

• Reduced insulin clearance increases hypoglycaemia risk.

• Lower starting and maintenance doses needed.

• Close monitoring and more frequent dose adjustments as kidney function changes.

Insulin Onset, Peak, and Duration Table

References

• NICE, “Type 1 diabetes in adults: diagnosis and management”

• NICE, “Type 2 diabetes in adults: management”

• NHS, “Insulin and diabetes”

• British National Formulary, “Insulins”

• Diabetes UK, “Insulin treatment”