What is the equivalent dose of NPH (neutral protamine Hagedorn) insulin for 26 units of Lantus (insulin glargine)?

Converting Lantus 26 Units to NPH Insulin

When converting from Lantus (insulin glargine) to NPH insulin, a 1:1 conversion is appropriate for the total daily dose, but the NPH dose should be split into two injections with approximately 80% of the original Lantus dose. 1

Conversion Algorithm

1. Total NPH daily dose calculation:

   • Start with 80% of current Lantus dose: 26 units × 0.8 = 20.8 units (round to 21 units total daily NPH)

2. NPH distribution:

   • Morning dose (2/3 of total): 14 units
   • Evening dose (1/3 of total): 7 units

Rationale for Conversion

The conversion from Lantus to NPH requires consideration of several important factors:

• Pharmacokinetic differences: Lantus is a long-acting basal insulin with no pronounced peak and approximately 24-hour duration, while NPH has an intermediate duration (12-18 hours) with a peak effect 4-10 hours after injection 2

• Dosing frequency: Lantus is administered once daily, while NPH typically requires twice-daily dosing to provide adequate 24-hour basal coverage 1

• Risk of hypoglycemia: NPH has a higher risk of hypoglycemia, especially nocturnal hypoglycemia, compared to Lantus due to its peak action 3

Monitoring After Conversion

After converting from Lantus to NPH, careful monitoring is essential:

• Check fasting blood glucose daily
• Monitor for hypoglycemia, particularly during peak NPH action times (4-10 hours after injection)
• Adjust doses based on individual response:
  • For hypoglycemia: determine cause; if no clear reason, lower corresponding dose by 10-20% 1
  • For persistent hyperglycemia: increase dose by 2 units every 3 days until target fasting glucose is reached 1

Common Pitfalls to Avoid

• Maintaining once-daily dosing: Unlike Lantus, NPH should be administered twice daily to provide adequate 24-hour coverage
• Using full 1:1 conversion: Starting with 80% of the Lantus dose reduces risk of hypoglycemia during transition
• Ignoring timing of injections: Morning NPH dose should be given before breakfast, and evening dose at bedtime
• Overlooking monitoring needs: More frequent glucose monitoring is needed after switching insulins 4

Special Considerations

If the patient experiences frequent hypoglycemia after conversion to NPH, consider:

• Further reducing the NPH dose
• Adjusting the timing of injections
• Evaluating if switching back to a long-acting analog might be more appropriate 1

Remember that the conversion approach should be adjusted based on glucose monitoring results, with the primary goal of maintaining glycemic control while minimizing hypoglycemia risk.