What is the appropriate dose of Lantus (insulin glargine) for a patient based on their current Humalog (insulin lispro) usage?

Determining Lantus Dose Based on Humalog Usage

For patients with type 1 diabetes on a basal-bolus regimen, calculate the total daily insulin dose (TDD) by adding all Humalog doses together, then give approximately 40-50% of that TDD as Lantus once daily, with the remaining 50-60% continuing as Humalog divided among meals. 1

Type 1 Diabetes: Standard Basal-Bolus Split

The fundamental principle is that basal insulin (Lantus) should represent 40-60% of the total daily insulin requirement, with prandial insulin (Humalog) comprising the remainder. 1

Calculation Algorithm:

1. Add up all Humalog doses from the past 24 hours to determine current prandial insulin usage 1
2. Divide the total Humalog dose by 0.5 to estimate TDD (since Humalog represents approximately 50% of total needs) 1
3. Give 40-50% of the calculated TDD as Lantus once daily 1
4. Continue the remaining 50-60% as Humalog divided among three meals 1

Example: If a patient is receiving 30 units of Humalog total per day (10 units before each meal), the estimated TDD is 60 units. Give 24-30 units of Lantus once daily (40-50% of 60 units), and continue 30-36 units of Humalog divided among meals 1.

Weight-Based Verification:

For metabolically stable type 1 diabetes patients, the typical TDD is 0.5 units/kg/day, split 50% basal and 50% prandial. 1 This provides a cross-check for your calculations 1.

• Higher doses (up to 1.0 units/kg/day or more) are required during puberty, pregnancy, and acute illness 1
• Lower doses (0.2-0.6 units/kg/day) may be needed during the honeymoon phase or with residual beta-cell function 1

Type 2 Diabetes: Different Approach

For type 2 diabetes patients, do NOT calculate Lantus based on Humalog usage. Instead, start Lantus at 10 units once daily or 0.1-0.2 units/kg/day, regardless of any correction insulin (Humalog) they've been receiving 1, 2.

Key Distinction:

• Type 2 diabetes patients typically start with basal-only insulin therapy 1
• Prandial insulin (Humalog) is only added later if basal insulin alone fails to achieve glycemic targets after 3-6 months 1
• When adding prandial insulin to type 2 diabetes patients, start with 4 units before the largest meal or 10% of the current basal dose 1

Critical Threshold: Recognizing Overbasalization

When Lantus exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, adding or intensifying prandial insulin becomes more appropriate than continuing to escalate basal insulin alone. 1

Clinical Signs of Overbasalization:

• Basal insulin dose >0.5 units/kg/day 1
• Bedtime-to-morning glucose differential ≥50 mg/dL 1
• Hypoglycemia episodes 1
• High glucose variability 1

Titration After Initial Dosing

Increase Lantus by 2-4 units every 3 days until fasting blood glucose reaches 80-130 mg/dL. 1

• If fasting glucose ≥180 mg/dL: increase by 4 units every 3 days 1
• If fasting glucose 140-179 mg/dL: increase by 2 units every 3 days 1
• If hypoglycemia occurs: reduce dose by 10-20% immediately 1

Special Considerations

Lantus must be given concomitantly with short-acting insulin (Humalog) in type 1 diabetes patients. 2 Lantus provides basal coverage only and cannot control postprandial glucose excursions 1.

Administer Lantus at the same time every day, though the specific time can be chosen based on patient preference. 2 Do not dilute or mix Lantus with any other insulin 2.

For patients requiring twice-daily Lantus dosing (due to inadequate 24-hour coverage), split the total daily Lantus dose into two equal doses given 12 hours apart. 1 This is particularly relevant for type 1 diabetes patients with high glycemic variability 1.