Lantus Dosing When Converting from Insulin Pump
For a type 2 diabetic using 29 units total daily insulin on a pump, start Lantus at 23 units once daily (80% of the total pump dose).
Conversion Algorithm
When transitioning from continuous subcutaneous insulin infusion (pump) to basal insulin like Lantus, the FDA-approved approach is clear 1:
- Calculate 80% of total daily pump insulin: 29 units × 0.80 = 23.2 units (round to 23 units)
- This dose reduction minimizes hypoglycemia risk during the transition
- Administer once daily at the same time each day
Rationale for Dose Reduction
The 80% conversion factor is specifically recommended by the Lantus prescribing information when converting from twice-daily NPH insulin to once-daily Lantus 1. While the label doesn't explicitly address pump-to-Lantus conversion, this same principle applies because:
- Pump basal rates provide continuous insulin delivery with precise pharmacokinetics
- Lantus has a different absorption profile than pump-delivered insulin
- The dose reduction buffer protects against hypoglycemia during the adjustment period
Important Caveats
Do not simply use the "insulin-naive" starting dose of 10 units 2, 1. That recommendation applies only to patients never previously treated with insulin. Your patient is already insulin-experienced at 29 units daily, making 10 units dangerously inadequate and likely to cause hyperglycemia.
Monitor closely during transition:
- Check fasting blood glucose daily for the first week
- Titrate upward by 2-4 units every 3-7 days if fasting glucose remains >130 mg/dL 2
- Watch for hypoglycemia, especially if the patient was using significant bolus insulin on the pump
Addressing the Basal-Bolus Split
If the 29 units on the pump included both basal and bolus components, you need to determine the basal-only amount first. However, the question states "total insulin used" without specifying basal vs. bolus breakdown. In the absence of that detail, the safest approach is to assume the 29 units represents total daily dose and start Lantus at 80% (23 units), then add mealtime insulin coverage separately if needed based on postprandial glucose monitoring 2, 3.
If basal insulin alone proves insufficient (HbA1c remains above goal after optimizing Lantus to 0.5 units/kg/day), consider adding mealtime rapid-acting insulin starting at 4 units per meal or 10% of basal dose per meal 2, 3.