What adjustments should be made to the insulin regimen of an adult patient with diabetes mellitus (DM) who is currently taking Lantus (insulin glargine) 34 units and bolus insulin (aspart or lispro) doses of 10 units in the morning and 10 units in the afternoon, presenting with hyperglycemia?

Insulin Regimen Adjustment for Hyperglycemia

This patient requires immediate intensification of both basal and prandial insulin coverage—increase Lantus by 4 units every 3 days until fasting glucose reaches 80-130 mg/dL, and add 4 units of rapid-acting insulin before lunch to address the severe postprandial hyperglycemia. 1

Immediate Basal Insulin Adjustment

Your fasting blood sugar of 191 mg/dL indicates inadequate basal insulin coverage. The American Diabetes Association recommends increasing basal insulin by 4 units every 3 days when fasting glucose is ≥180 mg/dL until reaching the target of 80-130 mg/dL 1. For your current Lantus dose of 34 units, increase to 38 units immediately, then continue increasing by 4 units every 3 days based on fasting glucose readings 1.

• Monitor fasting blood glucose daily during this titration phase 1
• Continue these 4-unit increments every 3 days until fasting glucose consistently falls between 80-130 mg/dL 1
• If hypoglycemia occurs without clear cause, reduce the dose by 10-20% immediately 1

Critical Problem: Postprandial Hyperglycemia Requires Prandial Insulin

Your post-lunch blood sugar of 290 mg/dL cannot be corrected by increasing basal insulin alone—this requires adding mealtime insulin coverage. 1 Basal insulin (Lantus) is designed to control fasting and between-meal glucose levels, not postprandial hyperglycemia 1. Continuing to escalate basal insulin to address post-lunch hyperglycemia leads to "overbasalization," a dangerous pattern where excessive basal insulin masks the need for mealtime coverage 1.

Add Prandial Insulin Before Lunch

• Start with 4 units of rapid-acting insulin (aspart or lispro) before lunch 1
• Alternatively, use 10% of your current basal dose (approximately 3-4 units based on 34 units Lantus) 1
• Administer this insulin 0-15 minutes before eating 1, 2
• Titrate by 1-2 units every 3 days based on 2-hour post-lunch glucose readings, targeting <180 mg/dL 1

Warning Signs of Overbasalization

Monitor for these clinical signals that indicate you need prandial insulin rather than more basal insulin: 1

• Basal insulin dose >0.5 units/kg/day (for a 70 kg patient, this would be >35 units—you're approaching this threshold) 1
• Large bedtime-to-morning glucose differential (≥50 mg/dL drop overnight) 1
• Episodes of hypoglycemia 1
• High glucose variability throughout the day 1

Foundation Therapy: Ensure Metformin is Optimized

Verify you are taking metformin at maximum tolerated dose (up to 2000-2550 mg daily) unless contraindicated. 1 The combination of metformin and insulin provides superior glycemic control with reduced insulin requirements and less weight gain compared to insulin alone 1, 2. Metformin should be continued when intensifying insulin therapy 1.

Monitoring Requirements

• Check fasting blood glucose every morning during titration 1
• Check pre-lunch and 2-hour post-lunch glucose to guide prandial insulin adjustments 1
• Record all glucose values to guide dose adjustments every 3 days 1
• Reassess every 3-6 months once stable to evaluate overall glycemic control and HbA1c 1

Common Pitfalls to Avoid

• Do not continue escalating Lantus beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia, as this leads to increased hypoglycemia risk without improved control 1
• Do not blame your morning bolus insulin for the post-lunch hyperglycemia—the morning bolus (rapid-acting analog) has a duration of only 3-5 hours and is designed to control post-breakfast glucose, not pre-lunch or post-lunch levels 1
• Do not use correction insulin alone—you need scheduled prandial insulin coverage, not just reactive correction doses 1
• Do not stop metformin when intensifying insulin unless contraindicated, as this leads to higher insulin requirements and more weight gain 1

Expected Timeline

• Basal insulin adjustments every 3 days until fasting glucose reaches target 1
• Prandial insulin adjustments every 3 days based on postprandial readings 1
• Most patients achieve fasting glucose targets within 2-3 weeks of systematic titration 1
• Consider adding prandial insulin to other meals if HbA1c remains above target after 3-6 months despite controlled fasting and post-lunch glucose 1