What is the starting dose of Lantus (insulin glargine) for a patient transitioning off an insulin drip with significant insulin resistance and impaired glycemic control?

Lantus Dosing for Transition from Insulin Drip

For this 103 kg patient with severe hyperglycemia (A1c 13.1) transitioning off an insulin drip, start Lantus at 60-80% of the average hourly insulin infusion rate over the preceding 12-24 hours, administered 2-4 hours before discontinuing the drip. 1

Calculating the Initial Dose

Calculate the total daily subcutaneous insulin requirement as follows:

• Determine the average hourly insulin infusion rate over the last 12-24 hours 1
• Multiply by 24 hours to get the total daily requirement 1
• Use 60-80% of this amount as the total daily subcutaneous dose 1
• Administer approximately 50% as basal insulin (Lantus) and 50% as prandial insulin 1

Example calculation: If the patient averaged 2 units/hour on the drip:

• 2 units/hour × 24 hours = 48 units total daily dose
• 48 units × 0.7 (70%) = 33.6 units subcutaneous total
• Lantus dose = ~17 units once daily
• Prandial insulin = ~16 units divided among meals 1

Alternative Weight-Based Approach

If drip data is unavailable or unreliable, use weight-based dosing:

• For severe hyperglycemia with significant insulin resistance (BMI 38, A1c 13.1), start with 0.3-0.5 units/kg/day total daily dose 1, 2
• For this 103 kg patient: 0.4 units/kg × 103 kg = 41 units total daily dose
• Lantus dose = ~20 units once daily (approximately 50% of total) 1, 2
• Divide remaining dose as prandial insulin 1

Critical Timing Considerations

Administer the first dose of Lantus 2-4 hours BEFORE discontinuing the insulin drip to ensure adequate overlap and prevent rebound hyperglycemia 1. This timing is essential because Lantus requires several hours to reach therapeutic levels 1.

Basal-Bolus Regimen Required

This patient requires a full basal-bolus regimen, not basal insulin alone:

• The severe hyperglycemia (A1c 13.1) and high insulin requirements indicate both inadequate basal coverage and significant postprandial excursions 1, 3
• Add rapid-acting insulin before each meal, starting with 4 units per meal or 10% of the basal dose 1, 2
• Include correction insulin for blood glucose >180 mg/dL 1

Titration Protocol

Increase Lantus dose systematically:

• Titrate by 2-4 units every 3 days based on fasting blood glucose 1, 2
• Target fasting glucose 80-130 mg/dL 1
• If fasting glucose ≥180 mg/dL, increase by 4 units every 3 days 2, 3
• If fasting glucose 140-179 mg/dL, increase by 2 units every 3 days 2
• For hypoglycemia, reduce dose by 10-20% 1

Common Pitfalls to Avoid

Do not use sliding scale insulin alone as the sole regimen for this patient with known diabetes and severe hyperglycemia—this approach is strongly discouraged and associated with poor outcomes 1.

Avoid overbasalization: Once Lantus exceeds 0.5 units/kg/day (~50 units for this patient) without achieving glycemic targets, intensify prandial insulin rather than continuing to escalate basal insulin 1, 2, 3. Signs of overbasalization include hypoglycemia, high glucose variability, and bedtime-to-morning glucose differential ≥50 mg/dL 2, 3.

Ensure adequate monitoring: Daily fasting blood glucose monitoring is essential during titration, with reassessment every 3 days during active dose adjustments 1, 2.

Special Considerations for This Patient

The combination of high BMI (38), severe hyperglycemia (A1c 13.1), and normal renal function (Cr 0.77) suggests significant insulin resistance requiring higher insulin doses than typical starting recommendations 1, 2. The patient will likely need 0.5-1.0 units/kg/day total insulin (50-100 units daily) to achieve glycemic control 1, 2.

Continue metformin unless contraindicated as the foundation of therapy, even while intensifying insulin 1, 3. Consider adding a GLP-1 receptor agonist once stable to improve glycemic control while minimizing weight gain 1, 3.