What is the starting dose of Lantus (insulin glargine) for a patient previously taking another form of insulin or diabetes medication?

Starting Dose of Lantus When Transitioning from Another Insulin

For patients with type 2 diabetes previously on insulin, start Lantus at 0.1-0.2 units/kg/day (typically 10 units once daily for most patients), and for those with type 1 diabetes, use 0.4-1.0 units/kg/day total daily insulin with approximately 40-50% given as Lantus. 1, 2

Type 2 Diabetes: Transitioning from Other Insulin

When converting from another basal insulin (NPH, detemir) to Lantus, use a unit-to-unit conversion as the starting point, then titrate based on fasting glucose. 1 However, if the patient was on high-dose home insulin (≥0.6 units/kg/day), reduce the total daily dose by 20% to prevent hypoglycemia. 1

Specific Conversion Scenarios:

• From NPH or detemir to Lantus: Convert unit-to-unit, but if the patient was on twice-daily NPH, the total daily NPH dose can be given as a single daily Lantus dose 1, 3
• From detemir to glargine: The total daily dose of glargine should be approximately 38% lower than the total daily dose of detemir (or conversely, detemir requires 38% higher dosing than glargine for equivalent control) 1
• From premixed insulin (e.g., NovoMix, Mixtard): Calculate the total daily insulin dose from the premixed regimen, then split 50% as Lantus once daily and 50% as prandial insulin divided among three meals 1

Titration Algorithm After Conversion:

• Increase by 2 units every 3 days if fasting glucose is 140-179 mg/dL 1, 4
• Increase by 4 units every 3 days if fasting glucose is ≥180 mg/dL 1, 4
• Target fasting glucose: 80-130 mg/dL 1, 4
• If hypoglycemia occurs, reduce dose by 10-20% immediately 1

Type 1 Diabetes: Transitioning from Other Insulin

For type 1 diabetes, calculate total daily insulin requirements at 0.4-1.0 units/kg/day (typically 0.5 units/kg/day for metabolically stable patients), with 40-50% given as Lantus and 50-60% as prandial insulin. 1, 2

Conversion from Insulin Pump:

When transitioning from an insulin pump to Lantus injections, use the 24-hour basal rate from the pump as the starting Lantus dose, typically divided into two doses given 12 hours apart (since type 1 patients often require twice-daily Lantus for adequate 24-hour coverage). 2, 3

Conversion from Multiple Daily Injections:

Add up the total current basal insulin dose (NPH or detemir), and convert unit-to-unit to Lantus, maintaining the same total daily prandial insulin dose. 1

Critical Thresholds and When to Add Prandial Coverage

When basal insulin 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 Signs of "overbasalization" include:

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

Special Population Dose Adjustments

High-Risk Patients Requiring Lower Doses:

• Elderly (>65 years): Start with 0.1-0.25 units/kg/day 1
• Renal impairment (eGFR <60 mL/min/1.73 m²): Start with 0.1-0.25 units/kg/day; for CKD Stage 5, reduce total daily insulin by 50% for type 2 diabetes or 35-40% for type 1 diabetes 1
• Poor oral intake or acute illness: Use 0.1-0.25 units/kg/day 1
• Patients with retinopathy: Consider starting dose of 0.12 units/kg/day 5

Patients on High-Dose Home Insulin:

For hospitalized patients previously on ≥0.6 units/kg/day at home, reduce the total daily dose by 20% upon admission to prevent hypoglycemia. 1

Foundation Therapy Considerations

Continue metformin at maximum tolerated dose (up to 2000-2550 mg daily) when initiating or converting to Lantus, as this combination provides superior glycemic control with reduced insulin requirements and less weight gain. 1, 4 Consider discontinuing sulfonylureas when advancing beyond basal-only insulin to prevent hypoglycemia. 1

Common Pitfalls to Avoid

• Never use sliding scale insulin as monotherapy when converting to Lantus; always establish a scheduled basal-bolus regimen 1
• Do not continue escalating Lantus beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia with prandial insulin 1
• Never discontinue metformin when starting or converting to insulin unless contraindicated 1, 4
• Do not delay insulin dose adjustments; 75% of hospitalized patients who experienced hypoglycemia had no basal insulin dose adjustment before the next administration 1

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration 1, 4
• Reassess adequacy of insulin dose at every clinical visit, looking for signs of overbasalization 1
• Check HbA1c every 3 months during intensive titration 1