Basal Insulin Initiation for Severe Hyperglycemia
For your patient with A1C 12.5% and fasting glucose 368 mg/dL, start insulin glargine (Lantus) at 0.2 units/kg once daily at the same time each day, and continue metformin unless contraindicated. 1
Why Insulin Glargine is the Best Choice
Insulin glargine is the preferred basal insulin because it provides consistent 24-hour coverage with once-daily dosing and has lower rates of severe hypoglycemia compared to NPH insulin 2. While detemir is also effective, it typically requires twice-daily dosing and higher total daily doses to achieve similar glycemic control 3, 4. For severe hyperglycemia like your patient's, glargine offers simpler dosing and comparable efficacy 3.
Starting Dose Calculation
Calculate the starting dose as 0.2 units/kg body weight once daily 1, 5. For example:
- 50 kg patient = 10 units once daily
- 70 kg patient = 14 units once daily
- 90 kg patient = 18 units once daily
This higher starting dose (0.2 units/kg rather than the standard 0.1 units/kg or 10 units) is appropriate because your patient has severe hyperglycemia with A1C >10% and fasting glucose >300 mg/dL 1. The American Diabetes Association guidelines specifically recommend more aggressive initial dosing (0.3-0.4 units/kg/day) for patients with A1C ≥9% or blood glucose ≥300-350 mg/dL 1.
Critical Titration Protocol
Increase the glargine dose by 4 units every 3 days until fasting blood glucose reaches 80-130 mg/dL, since your patient's fasting glucose is ≥180 mg/dL 1. If fasting glucose drops to 140-179 mg/dL during titration, reduce the increment to 2 units every 3 days 1.
If hypoglycemia occurs, immediately reduce the dose by 10-20% and determine the cause before resuming titration 1.
Foundation Therapy: Continue Metformin
Keep your patient on metformin (or start it if not already prescribed) unless contraindicated 1, 6. Metformin provides complementary glucose-lowering effects, reduces total insulin requirements, and should be continued even when intensifying insulin therapy 1. The optimal metformin dose is at least 2000 mg daily (1000 mg twice daily) unless limited by side effects or renal function 1.
When to Add Prandial Insulin
Recognize the critical threshold: when basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, add prandial insulin rather than continuing to escalate basal insulin alone 1. This prevents "overbasalization," which causes hypoglycemia and high glucose variability without improving A1C 1.
Start prandial insulin with 4 units of rapid-acting insulin (lispro, aspart, or glulisine) before the largest meal, or use 10% of the current basal dose 1. Increase prandial insulin by 1-2 units every 3 days based on 2-hour postprandial glucose readings 1.
Monitoring Requirements
Daily fasting blood glucose monitoring is essential during titration 1. Check A1C every 3 months during intensive titration to assess treatment effectiveness 1.
Reassess the insulin regimen at every clinical visit, looking specifically for signs of overbasalization: basal dose >0.5 units/kg/day, bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, or high glucose variability 1.
Common Pitfalls to Avoid
Do not delay insulin initiation or use inadequate starting doses in patients with severe hyperglycemia like yours 1. Prolonged exposure to A1C >9% increases complication risk 6.
Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia 1. This leads to suboptimal control and increased hypoglycemia risk 1.
Do not rely on sliding scale insulin alone without optimizing basal insulin first—this approach is ineffective for long-term management 6.
Do not mix or dilute glargine with any other insulin or solution due to its low pH formulation 5. It must be given as a separate injection 5.
Administration Details
Administer glargine subcutaneously into the abdomen, thigh, or deltoid, rotating injection sites within the same region to reduce lipodystrophy risk 5. Give at the same time every day, though the specific time (morning, evening, or bedtime) does not significantly affect efficacy 5.
Visually inspect the solution before each injection—it should be clear and colorless with no visible particles 5.