Initial Insulin Dosing for Severe Uncontrolled Type 2 Diabetes
Start basal‑bolus insulin immediately at 0.3–0.5 units/kg/day (37–62 units total daily dose for 123 kg), split 50% basal and 50% prandial, because an HbA1c of 10.9% with fasting glucose 250 mg/dL requires both basal and mealtime coverage from the outset. 1
Lantus (Basal Insulin) Dosing
Initial Dose
- Start Lantus at 18–31 units once daily at bedtime (0.15–0.25 units/kg for 123 kg), representing 50% of the total daily insulin requirement 1
- For severe hyperglycemia (HbA1c >10%, fasting glucose >250 mg/dL), use the higher end of the weight‑based range (0.3–0.5 units/kg/day total) rather than the standard 10‑unit starting dose 1, 2
Titration Protocol
- Increase Lantus by 4 units every 3 days when fasting glucose ≥180 mg/dL 1
- Increase by 2 units every 3 days when fasting glucose is 140–179 mg/dL 1
- Target fasting glucose: 80–130 mg/dL 1
- Critical threshold: When Lantus approaches 0.5 units/kg/day (≈62 units), stop further basal escalation and intensify prandial insulin instead to avoid "over‑basalization" 1
Prandial Insulin (Rapid‑Acting) Dosing
Initial Dose
- Start 6 units of rapid‑acting insulin (lispro, aspart, or glulisine) before each of the three largest meals (18 units total prandial), representing the remaining 50% of total daily insulin 1, 3
- Administer 0–15 minutes before meals for optimal postprandial control 1
Titration Protocol
- Increase each meal dose by 2 units every 3 days based on 2‑hour postprandial glucose readings 1
- Target postprandial glucose: <180 mg/dL 1
- If unexplained hypoglycemia occurs, reduce the implicated dose by 10–20% immediately 1
Correction (Sliding‑Scale) Insulin
Simplified Protocol
- Add 2 units of rapid‑acting insulin for pre‑meal glucose >250 mg/dL 1
- Add 4 units for pre‑meal glucose >350 mg/dL 1
- These correction doses are in addition to scheduled prandial insulin, never as a replacement 1
Individualized Correction Factor (ISF)
- Calculate ISF = 1500 ÷ total daily insulin dose 1
- For an initial total daily dose of 37 units: ISF = 1500 ÷ 37 = ≈40 mg/dL per unit
- Correction dose = (Current glucose – Target glucose of 125 mg/dL) ÷ ISF 1
Carbohydrate‑to‑Insulin Ratio (CIR)
Initial Ratio
- Start with 1 unit per 10 grams of carbohydrate (1:10 ratio) as a reasonable starting point 1
- Calculate individualized CIR = 450 ÷ total daily insulin dose 1
- For an initial total daily dose of 37 units: CIR = 450 ÷ 37 = ≈12 grams carbohydrate per unit (1:12 ratio)
Adjustment
- If 2‑hour postprandial glucose consistently exceeds 180 mg/dL, tighten the ratio (e.g., from 1:12 to 1:10 or 1:8) 1
- Adjust the CIR every 3 days based on postprandial glucose patterns 1
Foundation Therapy: Metformin
- Restart or optimize metformin to at least 1000 mg twice daily (2000 mg total) unless contraindicated 1, 3
- Metformin reduces total insulin requirements by 20–30% and provides superior glycemic control when combined with insulin 1
- Never discontinue metformin when adding or intensifying insulin therapy 1
Monitoring Requirements
Daily Monitoring During Titration
- Check fasting glucose every morning to guide Lantus adjustments 1
- Check pre‑meal glucose before each meal to calculate correction doses 1
- Obtain 2‑hour postprandial glucose after each meal to assess prandial adequacy 1
- Check bedtime glucose to evaluate overall daily pattern 1
Follow‑Up Schedule
- Reassess HbA1c every 3 months during intensive titration 1
- Monthly visits until HbA1c falls below 9%, then every 3 months 1
Expected Clinical Outcomes
- HbA1c reduction of 3–4% (from 10.9% to ≈7–8%) is achievable over 3–6 months with appropriate basal‑bolus therapy 1, 3
- 68% of patients achieve mean glucose <140 mg/dL with basal‑bolus therapy versus only 38% with sliding‑scale insulin alone 1
- Properly implemented basal‑bolus regimens do not increase hypoglycemia incidence compared with inadequate sliding‑scale approaches 1
Critical Pitfalls to Avoid
- Never use sliding‑scale insulin as monotherapy—it is condemned by all major diabetes guidelines as ineffective and unsafe 1
- Do not delay prandial insulin addition when fasting glucose is 250 mg/dL and HbA1c is 10.9%; both basal and prandial coverage are required from the start 1
- Do not continue escalating Lantus beyond 0.5 units/kg/day (≈62 units) without addressing postprandial hyperglycemia, as this leads to over‑basalization with increased hypoglycemia risk 1
- Do not discontinue metformin when starting insulin unless contraindicated; it must remain the foundational therapy 1, 3
- Never give rapid‑acting insulin solely at bedtime as a correction dose, as this markedly raises nocturnal hypoglycemia risk 1
Hypoglycemia Management
- Treat any glucose <70 mg/dL immediately with 15 grams of fast‑acting carbohydrate, recheck in 15 minutes, and repeat if needed 1
- If hypoglycemia occurs without an obvious cause, reduce the implicated insulin dose by 10–20% promptly 1
Summary Algorithm
| Parameter | Initial Dose | Titration | Target |
|---|---|---|---|
| Lantus (basal) | 18–31 U once daily at bedtime | +4 U every 3 days if FG ≥180 mg/dL; +2 U if FG 140–179 mg/dL | FG 80–130 mg/dL |
| Prandial insulin | 6 U before each meal (18 U total) | +2 U per meal every 3 days based on 2‑hr PPG | PPG <180 mg/dL |
| Correction insulin | +2 U if pre‑meal glucose >250 mg/dL; +4 U if >350 mg/dL | Adjust ISF if correction consistently fails | Pre‑meal glucose 90–150 mg/dL |
| Carb ratio | 1:10 or 1:12 (450 ÷ TDD) | Tighten ratio if PPG consistently >180 mg/dL | PPG <180 mg/dL |
| Metformin | 1000 mg twice daily | Titrate to 2000 mg daily | Continue unless contraindicated |
This regimen addresses the severe hyperglycemia (HbA1c 10.9%, fasting glucose 250 mg/dL) with immediate basal‑bolus therapy, systematic titration every 3 days, and metformin continuation to maximize efficacy while minimizing hypoglycemia risk.