What is the optimal Lantus (insulin glargine) dose and carb coverage dose for a 70-year-old type 2 diabetes patient with a body mass index (BMI) of 23, weighing 72 kg, currently taking 9 units of Lantus, with a bedtime blood glucose level of 232 mg/dL and a fasting blood glucose level of 198 mg/dL?

Lantus Dose Adjustment and Prandial Insulin Initiation

Increase Lantus to 18 units once daily (adding 9 units to the current dose) and initiate prandial insulin coverage with 4 units of rapid-acting insulin before the largest meal. 1, 2

Immediate Basal Insulin Adjustment

Your patient's fasting blood glucose of 198-232 mg/dL indicates severely inadequate basal insulin coverage. The current dose of 9 units is far below what this patient requires based on weight-based dosing. 1, 2

• For a 72 kg patient with persistent fasting hyperglycemia (≥180 mg/dL), increase the basal insulin dose by 4 units every 3 days until fasting glucose reaches 80-130 mg/dL 1, 2
• The recommended starting dose for insulin-naive type 2 diabetes patients is 0.1-0.2 units/kg/day, which translates to 7-14 units for this 72 kg patient 1, 2
• Since the patient is already on 9 units with fasting glucose ≥180 mg/dL, an immediate increase of 8-10 units (to approximately 17-19 units total) is appropriate 1, 2
• Continue titrating by 4 units every 3 days if fasting glucose remains ≥180 mg/dL 1, 2

Critical Threshold Monitoring

Watch for overbasalization when the basal dose exceeds 0.5 units/kg/day (36 units for this patient). 1

• Clinical signals of overbasalization include: basal dose >0.5 units/kg/day, bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, and high glucose variability 1
• When basal insulin approaches 0.5-1.0 units/kg/day without achieving glycemic targets, adding prandial insulin becomes more appropriate than continuing to escalate basal insulin alone 1, 2

Prandial Insulin Coverage

Given the elevated bedtime glucose (232 mg/dL), this patient likely has significant postprandial hyperglycemia requiring mealtime insulin coverage. 1, 2

• Start with 4 units of rapid-acting insulin (lispro, aspart, or glulisine) before the largest meal or use 10% of the basal dose 1, 2
• Titrate prandial insulin by 1-2 units or 10-15% every 3 days based on 2-hour postprandial glucose readings 1, 2
• Administer rapid-acting insulin 0-15 minutes before meals, not after eating 2

Carbohydrate Coverage Calculation

For ongoing carbohydrate coverage, establish an insulin-to-carbohydrate ratio (ICR) once the total daily dose (TDD) is determined. 1, 2

• A common starting ICR is 1 unit per 10-15 grams of carbohydrate 1
• The formula for ICR is 500 ÷ TDD (for regular insulin) or 450 ÷ TDD (for rapid-acting analogs) 1
• As the patient's insulin regimen stabilizes, recalculate the ICR based on the total daily dose 1, 2

Foundation Therapy Verification

Ensure the patient is on metformin unless contraindicated, as it remains the foundation of type 2 diabetes therapy. 1, 2

• Metformin should be continued when adding or intensifying insulin therapy 1, 2
• Metformin reduces total insulin requirements and provides complementary glucose-lowering effects 2

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration 1, 2
• Check pre-meal and 2-hour postprandial glucose to guide prandial insulin adjustments 1, 2
• Reassess adequacy of insulin dose at every clinical visit (every 3-6 months once stable) 1, 2
• If hypoglycemia occurs without clear cause, reduce the corresponding insulin dose by 10-20% immediately 1, 2

Common Pitfalls to Avoid

• Do not delay insulin intensification - prolonged exposure to hyperglycemia increases complication risk 2
• 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 and suboptimal control 1, 2
• Do not rely on sliding scale insulin alone - scheduled basal-bolus regimens are superior to reactive correction-only approaches 2, 3
• Avoid injecting into areas of lipodystrophy; rotate injection sites within the same region 4

Patient Education Essentials

• Teach proper insulin injection technique and site rotation 2
• Educate on recognition and treatment of hypoglycemia (treat at ≤70 mg/dL with 15 grams of fast-acting carbohydrate) 2
• Provide "sick day" management rules and insulin storage guidelines 2
• Equip patient with self-titration algorithms to improve glycemic control 2