What is the recommended insulin regimen for a type 1 diabetic patient using Lantus (insulin glargine) and 70/30 (NPH/regular insulin)?

Optimal Insulin Regimen for Type 1 Diabetes: Lantus and Rapid-Acting Insulin

For type 1 diabetic patients, the recommended insulin regimen should replace Lantus (insulin glargine) as basal insulin once daily combined with rapid-acting insulin before meals, discontinuing the use of 70/30 premixed insulin. 1, 2

Rationale for Basal-Bolus Regimen

Basal Insulin Component

• Lantus (insulin glargine) provides superior basal insulin coverage compared to NPH insulin:
  • No pronounced peak action, providing more stable 24-hour coverage 3
  • Reduced risk of hypoglycemia, especially nocturnal episodes 2, 4
  • More consistent absorption than intermediate-acting insulins 2
  • Typical starting dose: 16-24 units once daily 2

Bolus (Prandial) Insulin Component

• Rapid-acting insulin analogs (aspart, lispro, glulisine) should be used instead of 70/30 premixed insulin:
  • Better postprandial glucose control 2
  • More physiologic insulin delivery that matches carbohydrate intake 2
  • Reduced risk of hypoglycemia compared to regular insulin 2
  • Allows for flexible meal timing and carbohydrate counting 2

Why 70/30 Premixed Insulin Should Be Discontinued

70/30 premixed insulin (containing 70% NPH and 30% regular insulin) has significant disadvantages:

• Fixed ratio prevents individualized dosing of basal and bolus components
• Intermediate-acting component (NPH) has unpredictable peaks 2
• Requires rigid meal timing to avoid hypoglycemia 2
• Associated with increased hypoglycemia risk compared to basal-bolus regimens 2
• A study comparing premixed insulin to basal-bolus therapy showed comparable glycemic control but significantly increased hypoglycemia with premixed insulin 2

Implementation of Basal-Bolus Regimen

Starting Doses

1. Total daily insulin dose: 0.5 units/kg/day (range 0.4-1.0 units/kg/day) 1
2. Basal insulin (Lantus):
   • Approximately 50% of total daily dose 1
   • Administer once daily at the same time (bedtime preferred) 5
3. Prandial insulin:
   • Remaining 50% of total daily dose divided among meals 1
   • Administer rapid-acting insulin 5-15 minutes before meals 2

Dose Adjustments

• Basal insulin: Adjust based on fasting blood glucose levels
  • Target fasting glucose: 80-130 mg/dL
  • Increase/decrease by 1-2 units every 3-4 days until target is reached 1
• Prandial insulin: Adjust based on pre-meal and post-meal glucose levels
  • Consider carbohydrate counting: typically 1 unit per 10-15g carbohydrate 1
  • Add correction doses for high pre-meal glucose levels

Monitoring Recommendations

• Blood glucose monitoring at least 4 times daily (before meals and bedtime) 1
• Consider continuous glucose monitoring if available 2
• Target A1C <7.0% for most adults 2
• Assess for hypoglycemia, especially at night

Potential Pitfalls and How to Avoid Them

1. Hypoglycemia risk during transition:

   • Start with conservative insulin doses
   • More frequent monitoring during transition period
   • Educate patient on hypoglycemia recognition and treatment

2. Overlap between basal and bolus insulin:

   • Ensure Lantus is given at consistent times
   • Separate Lantus injection from rapid-acting insulin injections

3. Patient adherence challenges:

   • Provide education on carbohydrate counting
   • Simplify regimen when possible while maintaining physiologic insulin replacement
   • Consider insulin pens for easier administration

4. Special situations:

   • During illness: Never stop basal insulin, adjust bolus insulin as needed 1
   • Physical activity: May require reduced prandial insulin doses before exercise

The basal-bolus regimen with Lantus and rapid-acting insulin provides more physiologic insulin replacement, better glycemic control, and reduced hypoglycemia risk compared to premixed 70/30 insulin for patients with type 1 diabetes.