What is the recommended starting dose of Lantus (insulin glargine) for a patient with poorly controlled diabetes and an A1C of 12%?

Starting Dose of Lantus for A1C 12%

For a patient with poorly controlled diabetes and an A1C of 12%, start Lantus at 0.2 units/kg once daily OR 10 units once daily, whichever is higher, and aggressively titrate by 4 units every 3 days until fasting glucose reaches 80-130 mg/dL. 1, 2

Rationale for Higher Starting Dose

An A1C of 12% represents severe hyperglycemia requiring immediate and aggressive intervention. The standard starting dose of 0.1-0.2 units/kg/day applies to patients with mild-to-moderate hyperglycemia, but your patient falls into the category requiring more intensive therapy from the outset 1, 3.

• For severe hyperglycemia (A1C ≥9-10%), consider starting doses of 0.3-0.5 units/kg/day as total daily insulin 1, 3
• At A1C 12%, you should strongly consider immediate basal-bolus therapy rather than basal insulin alone, as this level indicates both inadequate basal coverage AND significant postprandial hyperglycemia 1, 3

Aggressive Titration Protocol

The key to success with A1C this elevated is aggressive, systematic titration:

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

Critical Threshold: When to Add Prandial Insulin

When basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day without achieving glycemic targets, add prandial insulin rather than continuing to escalate basal insulin alone 1, 3. This prevents "overbasalization"—a dangerous pattern where excessive basal insulin masks the need for mealtime coverage 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

Prandial Insulin Initiation

For A1C 12%, you will likely need to add prandial insulin within weeks:

• Start with 4 units of rapid-acting insulin before the largest meal, OR use 10% of the basal dose 1, 3
• Titrate prandial insulin by 1-2 units or 10-15% every 3 days based on 2-hour postprandial glucose readings 1

Essential Concurrent Therapy

Continue metformin at maximum tolerated dose (up to 2000-2550 mg daily) unless contraindicated 1, 3. The combination of metformin and insulin provides superior glycemic control with reduced insulin requirements and less weight gain compared to insulin alone 1, 3.

Discontinue sulfonylureas when advancing beyond basal-only insulin, as the combination significantly increases hypoglycemia risk 1, 3.

Expected Outcomes

With appropriate basal-bolus therapy at weight-based dosing:

• A1C reduction of 2-3% is achievable from current levels 3
• 68% of patients achieve mean blood glucose <140 mg/dL with proper basal-bolus therapy 3

Common Pitfalls to Avoid

• Do NOT start with only 10 units if the patient weighs >50 kg—use weight-based dosing (0.2 units/kg minimum) for severe hyperglycemia 1, 3
• Do NOT delay adding prandial insulin for months—prolonged severe hyperglycemia (A1C >9%) increases complication risk 3
• Do NOT rely on sliding scale insulin alone—it treats hyperglycemia reactively rather than preventing it 1, 3
• Do NOT continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia—this leads to overbasalization with increased hypoglycemia risk 1, 3

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration 1
• Check A1C every 3 months during intensive titration 1
• Reassess every 3 days during active titration to adjust dose 1