How do you initiate insulin therapy in a patient with Type 1 Diabetes Mellitus (Type 1 DM)?

Initiating Insulin Therapy in Type 1 Diabetes Mellitus

For patients with Type 1 Diabetes Mellitus, insulin therapy should be initiated with multiple daily injections of prandial and basal insulin at a starting dose of 0.5 units/kg/day, with approximately half as basal insulin and half as prandial insulin. 1

Initial Dosing Algorithm

1. Calculate Total Daily Insulin Dose:

   • Start with 0.5 units/kg/day for metabolically stable patients 1
   • Lower doses (0.2-0.6 units/kg/day) may be appropriate for young children or those in the honeymoon phase 1
   • Higher doses may be needed during puberty, pregnancy, or medical illness 1

2. Distribute the Total Daily Dose:

   • Approximately 50% as basal insulin (long-acting)
   • Approximately 50% as prandial insulin (rapid-acting) 1

3. Insulin Selection:

   • Basal insulin: Use long-acting insulin analogs (glargine, detemir, degludec) over NPH insulin to reduce hypoglycemia risk 1
   • Prandial insulin: Use rapid-acting insulin analogs over regular human insulin to reduce hypoglycemia risk 1

Administration Guidelines

• Basal insulin: Administer once daily at the same time each day 1
• Prandial insulin: Administer before meals, with timing based on:
  • Insulin formulation pharmacokinetics
  • Pre-meal blood glucose levels
  • Carbohydrate content of meals 1
• Injection technique:
  • Inject subcutaneously into abdomen, thigh, or deltoid 2
  • Use short needles (4-6 mm) to avoid intramuscular injection 1
  • Rotate injection sites to prevent lipohypertrophy 2

Dose Adjustment and Monitoring

• Titrate basal insulin based on fasting blood glucose levels, targeting 80-130 mg/dL 3
• Adjust prandial insulin doses based on:
  • Carbohydrate counting (1 unit per 10-15g carbohydrate as starting point)
  • Pre-meal blood glucose levels
  • Anticipated physical activity 1
• Monitor blood glucose frequently during initiation and dose adjustments 2
• Evaluate HbA1c every 3 months to assess overall glycemic control 3

Education Components

1. Carbohydrate counting: Teach patients to match prandial insulin to carbohydrate intake 1
2. Hypoglycemia management: Ensure patients can recognize and treat hypoglycemia, and always carry quick-acting carbohydrates 3
3. Sick day management: Provide guidelines for insulin adjustment during illness 1
4. Exercise considerations: Educate on insulin adjustment for physical activity 3

Common Pitfalls and How to Avoid Them

• Nocturnal hypoglycemia: Use long-acting insulin analogs instead of NPH insulin, as they have lower risk of nocturnal hypoglycemia 1
• Intramuscular injection: Use short needles and proper injection technique to avoid IM delivery, which can cause unpredictable absorption and hypoglycemia 1
• Lipohypertrophy: Teach proper site rotation to prevent lipohypertrophy, which can lead to erratic insulin absorption 1
• Overbasalization: Monitor for signs of excessive basal insulin, including nocturnal hypoglycemia or high glucose variability 3

Advanced Options

For patients not meeting glycemic targets with multiple daily injections, consider:

• Continuous subcutaneous insulin infusion (insulin pump) 1
• Continuous glucose monitoring to improve glycemic control 1
• Automated insulin delivery systems for those capable of using the device safely 1

By following this structured approach to insulin initiation in Type 1 Diabetes, you can help patients achieve optimal glycemic control while minimizing the risks of hypoglycemia and other complications.