What is the recommended approach for initiating insulin therapy in patients with diabetes?

Recommended Approach for Initiating Insulin Therapy in Diabetes

For patients with diabetes requiring insulin therapy, basal insulin should be initiated at 10 units per day or 0.1-0.2 units/kg of body weight, with subsequent dose titration based on self-monitored blood glucose levels. 1, 2

Initial Insulin Selection and Dosing

Type 1 Diabetes

• Start with multiple daily injections at diagnosis 3
• Initial dose: 0.4-1.0 units/kg/day of total insulin 2
  • Approximately one-third as basal insulin
  • Remaining two-thirds as prandial (bolus) insulin
• Use basal-bolus regimen with:
  • Long-acting insulin (glargine, detemir, degludec) once daily
  • Rapid-acting insulin (lispro, aspart, glulisine) before meals

Type 2 Diabetes

• Start with basal insulin when:

  • Oral medications fail to achieve glycemic targets
  • HbA1c ≥7.5% despite optimal oral therapy 3
  • HbA1c ≥10% or blood glucose ≥300 mg/dL (consider basal plus mealtime insulin) 1
  • Symptoms of hyperglycemia, ketosis, or unintentional weight loss are present 1

• Initial dosing:

  • 10 units/day or 0.1-0.2 units/kg/day 1, 2, 4
  • Continue metformin and consider continuing other oral agents 1, 2

Insulin Titration Process

Basal Insulin Titration

• Adjust dose by 2-4 units once or twice weekly until fasting glucose target is reached 2, 5
• Decrease dose by 2 units if hypoglycemia occurs 2
• Target fasting glucose: 80-130 mg/dL 5
• Evaluate for overbasalization if:
  • Basal dose exceeds 0.5 units/kg 1, 2
  • Significant difference between bedtime and morning glucose levels 1

When to Intensify Beyond Basal Insulin

• If HbA1c remains above target after optimizing basal insulin:
  • Consider adding GLP-1 receptor agonist before adding prandial insulin 1
  • Or add prandial insulin, starting with the largest meal 1
  • Initial prandial dose: 4 units or 10% of basal dose 1

Insulin Types and Considerations

Basal Insulin Options

• Long-acting analogs (glargine, detemir, degludec):
  • Lower risk of nocturnal hypoglycemia compared to NPH 1, 2, 6
  • More stable glucose profile 6
  • Administered once daily at same time each day 4

Prandial Insulin Options

• Rapid-acting analogs (lispro, aspart, glulisine) preferred over regular insulin 1
  • Administer 0-15 minutes before meals
  • Better postprandial glucose control 7

Special Considerations

• Monitoring: Self-monitoring of blood glucose is essential for dose adjustments 1, 2

  • Use fasting glucose to titrate basal insulin
  • Use pre- and post-meal glucose to titrate prandial insulin

• Hypoglycemia prevention:

  • Start with conservative doses in elderly patients or those with renal impairment 2
  • Use long-acting analogs rather than NPH to reduce nocturnal hypoglycemia 1, 6
  • Educate patients on hypoglycemia recognition and management 2

• Injection technique:

  • Rotate injection sites within same region to prevent lipohypertrophy 4, 3
  • Use shortest available needles (4-6mm) 3
  • Administer subcutaneously in abdomen, thigh, or deltoid 4

• Medication adjustments:

  • Continue metformin when initiating insulin 2
  • Consider discontinuing sulfonylureas, DPP-4 inhibitors when using complex insulin regimens 1
  • SGLT2 inhibitors or thiazolidinediones may be continued to improve glucose control and reduce insulin requirements 1

By following this structured approach to insulin initiation and titration, patients can achieve improved glycemic control with minimized risk of hypoglycemia, ultimately reducing diabetes-related morbidity and mortality.