What is the initial dose of Lantus (insulin glargine) for a 68-year-old male, weighing 252 pounds, with an Hemoglobin A1C (HbA1c) of 6.3, currently on Januvia (sitagliptin) 100 mg, glimepiride 4 mg, and metformin 1000 mg daily, who recently discontinued his previous medication due to recurrent yeast infections?

Starting Lantus Dose for This Patient

Start with 10 units of Lantus once daily at bedtime, then titrate by 2 units every 3 days until fasting glucose reaches 80-130 mg/dL. 1, 2

Rationale for Conservative Starting Dose

This patient's A1C of 6.3% indicates relatively good glycemic control despite discontinuing what was likely an SGLT2 inhibitor (given the recurrent yeast infections). The low A1C means he does NOT require aggressive insulin initiation—a standard starting dose of 10 units is appropriate rather than weight-based dosing of 0.1-0.2 units/kg (which would be 11-23 units for his 252 lb/114 kg weight). 1, 2

Key Clinical Considerations:

• His current A1C of 6.3% is already at or below most glycemic targets, suggesting his current oral regimen (Januvia, glimepiride, metformin) is providing substantial glucose control 1
• Starting with 10 units minimizes hypoglycemia risk, particularly important since he's already on glimepiride (a sulfonylurea that increases hypoglycemia risk when combined with insulin) 1, 2
• At age 68, he falls into a population requiring more conservative dosing to avoid hypoglycemia-related complications 1

Evidence-Based Titration Protocol

Increase the Lantus dose by 2 units every 3 days based on fasting glucose readings: 1, 2

• If fasting glucose is 140-179 mg/dL: increase by 2 units
• If fasting glucose is ≥180 mg/dL: increase by 4 units
• If fasting glucose is <80 mg/dL on more than 2 occasions per week: decrease by 2 units
• Target fasting glucose: 80-130 mg/dL 1, 2

For Hypoglycemia Management:

If hypoglycemia occurs without clear cause, reduce the dose immediately by 10-20% 1, 2

Critical Medication Management

Continue metformin 1000 mg daily unless contraindicated—metformin should be maintained when adding insulin as it reduces insulin requirements and provides complementary glucose-lowering effects 1, 2

Consider reducing or discontinuing glimepiride once insulin is titrated to therapeutic doses, as the combination significantly increases hypoglycemia risk 1, 3. The sulfonylurea becomes redundant once adequate insulin dosing is achieved and poses unnecessary hypoglycemia danger.

Continue Januvia 100 mg—DPP-4 inhibitors like sitagliptin are safe in combination with basal insulin and may reduce the need for aggressive insulin escalation 1

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration 1, 2
• Reassess every 3-6 months with A1C measurement 1
• Watch for signs of overbasalization if dose exceeds 0.5 units/kg/day (approximately 57 units for this patient): bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, or high glucose variability 2

Common Pitfalls to Avoid

Do not delay insulin titration—adjust every 3 days as planned rather than waiting weeks between adjustments, which unnecessarily prolongs time to glycemic targets 1, 2

Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day (57-114 units) without adding prandial insulin if A1C remains elevated, as this leads to "overbasalization" with increased hypoglycemia risk and suboptimal control 1, 2

Do not abruptly discontinue all oral medications when starting insulin—this causes rebound hyperglycemia 3

Expected Outcomes

With this conservative approach, expect gradual improvement in fasting glucose over 2-4 weeks. Given his already-controlled A1C of 6.3%, the primary goal is maintaining current control while addressing whatever hyperglycemia prompted the discontinued medication, rather than achieving dramatic A1C reduction. 1, 2