Insulin Therapy in Type 2 Diabetes

• Indications:
  • Progressive β-cell failure despite oral agents.
  • Severe hyperglycemia (e.g., HbA1c >10%).
  • Symptoms of hyperglycemia (e.g., polyuria, polydipsia).
  • Complications (e.g., DKA, HHS).
  • Pregnancy or planned pregnancy.
  • Rationale: Insulin is the most effective glucose-lowering therapy, particularly when oral agents fail.

• Types of Insulin:
  • Basal Insulin:
    • Long-acting (glargine, detemir, degludec).
    • Once-daily, peakless, mimics endogenous basal secretion.
    • Rationale: Maintains fasting glucose control.
  • Prandial Insulin:
    • Rapid-acting (lispro, aspart, glulisine).
    • Pre-meal administration, mimics postprandial insulin spikes.
    • Rationale: Controls postprandial glucose.
  • Premixed Insulin:
    • Fixed ratios of intermediate/rapid-acting insulin.
    • Convenient for patients with fixed meal schedules.
    • Rationale: Simplifies dosing for non-complex regimens.

• Dosing Strategies:
  • Basal-Bolus:
    • Basal insulin + prandial insulin before meals.
    • Titrate based on fasting and postprandial glucose.
    • Rationale: Mimics physiological insulin secretion.
  • Basal-Plus:
    • Basal insulin + 1–2 prandial doses for highest glucose excursions.
    • Rationale: Simplifies regimen for patients with mild postprandial spikes.
  • Premixed Insulin:
    • 1–2 injections/day, fixed ratios (e.g., 70/30).
    • Rationale: Suitable for patients with predictable meal patterns.

• Monitoring and Adjustments:
  • Self-Monitoring:
    • Capillary glucose checks (fasting, pre-/postprandial).
    • Continuous glucose monitoring (CGM) for tighter control.
    • Rationale: Guides titration and detects hypoglycemia.
  • HbA1c Targets:
    • <7.0% for most, <6.5% for selected patients (e.g., young, no CV disease).
    • Rationale: Balances glycemic control and hypoglycemia risk.

• Safety Considerations:
  • Hypoglycemia:
    • Risk increases with sulfonylureas, insulin, and tight control.
    • Rationale: Monitor closely, especially in elderly or frail patients.
  • Weight Gain:
    • Insulin often causes weight gain (1–4 kg initially).
    • Rationale: Counteract with lifestyle modifications or GLP-1 RAs.
  • Insulin Pumps:
    • Continuous subcutaneous insulin infusion (CSII) for tight control.
    • Rationale: Flexible, but requires patient education and adherence.

• Special Populations:
  • Pregnancy:
    • Insulin is the preferred therapy (avoid oral agents).
    • Rationale: Avoids fetal teratogenicity and achieves tight control.
  • Renal/ Hepatic Impairment:
    • Adjust doses; avoid certain insulins (e.g., NPH in renal failure).
    • Rationale: Clearance is altered; monitor closely.

• Emerging Therapies:
  • Inhaled Insulin (Afrezza):
    • Rapid-acting, non-invasive, but limited by lung disease.
    • Rationale: Alternative for patients with injection aversion.
  • Smart Insulin (e.g., Fiasp, Afrezza):
    • Ultra-rapid or inhaled options for postprandial control.
    • Rationale: Faster onset, shorter duration, reduces hypoglycemia.

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