Insulin

Main indications

• Mainstay of treatment for T1DM
• Some T2DM patients may need endogenous insulin

Mechanism of action

• Lowers blood sugar
• Aims to mimic normal physiological secretion of insulin so most T1DM patients will be on a basal-bolus regimen
  • Long-acting insulin 1-2 times a day and short-acting insulin before each meal

Short-acting insulins

• Soluble insulins, e.g. Actrapid, Humulin S, reach a peak 2-4 hours after injection
  • Action tends to persist after meals - predisposes to hypoglycaemia
• Insulin analogues, e.g. insulin aspart (NovoRapid), lispro (Humalog) and glulisine (Apidra), reach a peak 60-90 mins after injection
  • Disappear from circulation more rapidly than soluble insulin - preferred

Intermediate and long-acting insulins

• Isophane 'basal' insulins, e.g. Insulatart, Humulin, are intermediate to long acting with a peak action around 4-6 hours
• Analogue basal insulins, e.g. lantus (glargine), levemir (dertermir), have a longer duration of action with less peak activity and may be given once or twice a day

Contraindications and cautions

• Injection site should be rotated to prevent lipohypertrophy

Adverse effects

• Weight gain
• Risk of hypoglycaemia

Administration