Initial Lantus Dosing for Severe Hyperglycemia
For a patient with A1C 12.9% and blood glucose 305 mg/dL, start Lantus at 0.3-0.5 units/kg/day as part of an immediate basal-bolus insulin regimen, not basal insulin alone. 1
Why Basal-Bolus from the Start
This degree of hyperglycemia (A1C ≥10%, glucose ≥300 mg/dL) warrants both basal and prandial insulin coverage immediately rather than starting with basal insulin alone. 1, 2 At this A1C level, basal insulin monotherapy will be insufficient—you need to address both fasting and postprandial hyperglycemia from day one. 1
Specific Dosing Algorithm
Calculate total daily insulin dose:
- Use 0.3-0.5 units/kg/day as your starting point for severe hyperglycemia 1, 2
- For a 70 kg patient: 21-35 units total daily dose
- For a 90 kg patient: 27-45 units total daily dose
Split the dose 50:50:
- Give 50% as Lantus once daily (bedtime or morning) 1, 2
- Give 50% as rapid-acting insulin divided among three meals 1, 2
Example for 80 kg patient:
- Total daily dose: 24-40 units (using 0.3-0.5 units/kg)
- Lantus: 12-20 units once daily
- Rapid-acting insulin: 4-7 units before each meal
Titration Protocol
Basal insulin adjustment:
- Increase Lantus by 4 units every 3 days if fasting glucose ≥180 mg/dL 1
- Increase by 2 units every 3 days if fasting glucose 140-179 mg/dL 1
- Target fasting glucose: 80-130 mg/dL 1
Prandial insulin adjustment:
- Increase each meal dose by 1-2 units every 3 days based on 2-hour postprandial glucose 1
- Target postprandial glucose: <180 mg/dL 1
Critical Threshold to Monitor
Watch for overbasalization when Lantus exceeds 0.5 units/kg/day (36 units for 70 kg patient). 1 At this point, add or intensify prandial insulin rather than continuing to escalate basal insulin. 1 Clinical signals include:
- Basal dose >0.5 units/kg/day
- Bedtime-to-morning glucose drop ≥50 mg/dL
- Hypoglycemia episodes
- High glucose variability 1
Essential Concurrent Therapy
Continue metformin at maximum tolerated dose (up to 2000-2500 mg daily) unless contraindicated. 1, 2 This combination provides superior glycemic control with reduced insulin requirements and less weight gain compared to insulin alone. 1, 2
Discontinue sulfonylureas when implementing basal-bolus insulin to prevent severe hypoglycemia. 1, 2
Expected Outcomes
With appropriate basal-bolus therapy at weight-based dosing, expect A1C reduction of 2-3% from current levels. 2 With proper implementation, 68% of patients achieve mean blood glucose <140 mg/dL. 2
Common Pitfalls to Avoid
Never start with basal insulin alone at this A1C level. Blood glucose of 305 mg/dL with A1C 12.9% reflects both inadequate basal coverage AND postprandial excursions requiring mealtime insulin from the outset. 1
Never rely on sliding scale insulin as monotherapy. This approach is explicitly condemned by all major diabetes guidelines and treats hyperglycemia reactively rather than preventing it. 1, 2
Never delay insulin intensification. Prolonged severe hyperglycemia (months at A1C >9%) significantly increases complication risk. 2
Monitoring Requirements
- Check fasting blood glucose daily during titration 1
- Check pre-meal and 2-hour postprandial glucose to guide prandial insulin adjustments 1
- Reassess every 3 days during active titration 1
- Check A1C every 3 months during intensive titration 1