How do I adjust my Lantus (insulin glargine) and bolus insulin doses to achieve optimal blood glucose control on a basal-bolus regimen?

Adjusting Lantus and Bolus Insulin on a Basal-Bolus Regimen

Immediate Dose Optimization Strategy

Your current Lantus dose of 34 units should be titrated aggressively by 4 units every 3 days until your fasting blood glucose consistently reaches 80-130 mg/dL, while simultaneously optimizing your bolus insulin doses based on 2-hour postprandial glucose readings. 1

Basal Insulin (Lantus) Titration Algorithm

Fasting Glucose-Based Adjustments

• If fasting glucose ≥180 mg/dL: Increase Lantus by 4 units every 3 days 1
• If fasting glucose 140-179 mg/dL: Increase Lantus by 2 units every 3 days 1
• Target fasting glucose: 80-130 mg/dL 1
• If hypoglycemia occurs (<70 mg/dL) without clear cause: Reduce Lantus dose by 10-20% immediately 1

Critical Threshold Warning

• When your Lantus dose exceeds 0.5 units/kg/day (approximately 35-40 units for a 70 kg person), focus on optimizing bolus insulin rather than continuing to escalate basal insulin alone 1
• Signs you've reached this threshold include: bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia episodes, and high glucose variability throughout the day 1

Bolus Insulin Adjustment Protocol

Initial Bolus Dosing

• If you're starting bolus insulin: Begin with 4 units of rapid-acting insulin before your largest meal, or use 10% of your current Lantus dose (approximately 3-4 units based on 34 units Lantus) 1
• Timing is critical: Administer rapid-acting insulin 0-15 minutes before meals, never after eating 1

Bolus Insulin Titration

• Check 2-hour postprandial glucose after each meal to guide adjustments 1
• If postprandial glucose consistently >180 mg/dL: Increase that meal's bolus dose by 1-2 units or 10-15% every 3 days 1
• Target postprandial glucose: <180 mg/dL 1
• If hypoglycemia occurs: Reduce the corresponding bolus dose by 10-20% 1

Carbohydrate Coverage Calculation

• Insulin-to-carbohydrate ratio: Start with 1 unit per 10-15 grams of carbohydrate 1
• Formula for precise calculation: 450 ÷ total daily insulin dose = grams of carbohydrate covered by 1 unit 1
• Example: If your total daily dose is 60 units (34 basal + 26 bolus), your ratio would be 450 ÷ 60 = 7.5 grams carbohydrate per unit

Correction Insulin Dosing

• Calculate your insulin sensitivity factor (ISF): 1500 ÷ total daily insulin dose 1
• Example: If total daily dose is 60 units, ISF = 1500 ÷ 60 = 25 mg/dL drop per unit
• Use this to correct pre-meal hyperglycemia: (Current glucose - Target glucose) ÷ ISF = correction dose 1

Daily Monitoring Requirements

• Check fasting glucose every morning during titration to guide Lantus adjustments 1
• Check pre-meal glucose before each meal to calculate correction doses 1
• Check 2-hour postprandial glucose to assess adequacy of bolus insulin 1
• Reassess every 3 days during active titration 1
• Reassess every 3-6 months once stable to evaluate HbA1c and overall control 1

Foundation Therapy: Continue Metformin

• Metformin must be continued at maximum tolerated dose (up to 2000-2550 mg daily) unless contraindicated 1
• The combination of metformin with insulin provides superior glycemic control with reduced insulin requirements and less weight gain compared to insulin alone 1

Critical Pitfalls to Avoid

• Never continue escalating Lantus beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia with bolus insulin—this leads to "overbasalization" with increased hypoglycemia risk and suboptimal control 1
• Never give rapid-acting insulin at bedtime to correct high glucose—this significantly increases nocturnal hypoglycemia risk 1
• Never rely on correction insulin alone—scheduled basal-bolus therapy with correction doses as adjunct is superior to sliding scale monotherapy 1
• Never discontinue metformin when intensifying insulin unless contraindicated 1

When to Add Prandial Insulin to Additional Meals

• Start with one meal (typically the largest) and add bolus insulin to other meals sequentially based on glucose patterns 1
• Add to a second meal if pre-meal glucose before that meal consistently exceeds 140 mg/dL despite optimized basal insulin 1
• Progress to three-meal coverage if needed to achieve HbA1c <7% 1

Hypoglycemia Management

• Treat any glucose <70 mg/dL immediately with 15 grams of fast-acting carbohydrate 1
• Recheck in 15 minutes and repeat treatment if needed 1
• Always carry fast-acting carbohydrates with you 1
• After treating hypoglycemia: Identify the cause and reduce the corresponding insulin dose by 10-20% 1

When to Contact Your Healthcare Provider

• Fasting glucose remains >180 mg/dL after 2-3 weeks of titration 1
• Lantus dose exceeds 0.5 units/kg/day without achieving fasting glucose targets 1
• Recurrent hypoglycemia despite dose reductions 1
• HbA1c remains above target after 3-6 months despite achieving fasting glucose goals—this indicates need for intensified prandial coverage or alternative therapy 1