Medium Insulin Dose for Severe Hyperglycemia
For a patient with fasting glucose ~600 mg/dL on metformin and only 18 units of basal insulin with a low-dose sliding scale, you should calculate total daily insulin dose at 0.4-0.5 U/kg/day, split 50% basal and 50% prandial (nutritional) insulin, and use the "usual" column for correction doses. This represents a medium-intensity insulin regimen appropriate for severe hyperglycemia (>300 mg/dL).
Calculating the Medium Dose
With a glucose of 600 mg/dL, this patient falls into the severe hyperglycemia category requiring aggressive insulin therapy. According to the Endocrine Society guidelines 1:
- For blood glucose 201-400 mg/dL: Start 0.5 U/kg/day total daily dose (TDD)
- For blood glucose >400 mg/dL: This patient exceeds even the high-dose threshold
For a 70 kg patient, this translates to:
- Total daily dose: 35 units (0.5 U/kg × 70 kg)
- Basal insulin (glargine): ~18 units (50% of TDD) - which happens to match current dose
- Prandial insulin: ~6 units before each meal (remaining 50% divided by 3 meals)
The Correction Scale: Medium ("Usual") Column
The current "low-dose sliding scale" is inadequate. Switch to the "usual" correction column 1:
| Blood Glucose (mg/dL) | Usual Correction Dose |
|---|---|
| 141-180 | 4 units |
| 181-220 | 6 units |
| 221-260 | 8 units |
| 261-300 | 10 units |
| 301-350 | 12 units |
| 351-400 | 14 units |
| ≥400 | 16 units |
This correction dose is added to the scheduled prandial insulin dose.
Complete Regimen Structure
Discontinue metformin upon hospitalization 1 - oral agents are contraindicated in acute severe hyperglycemia and delay achieving glycemic targets.
Basal-bolus regimen:
- Insulin glargine 18 units at bedtime (or morning, per patient preference)
- Rapid-acting insulin 6 units before each meal
- Correction doses from "usual" column added to prandial doses
Important Caveats
Adjust for patient-specific factors 1:
- If age ≥70 years or GFR <60 mL/min: Reduce starting dose to 0.2-0.3 U/kg/day
- If insulin-resistant (on corticosteroids, BMI >35): Consider "insulin-resistant" correction column (starting at 6 units for glucose 141-180 mg/dL)
The AACE algorithm 2 provides similar guidance for severe hyperglycemia:
- For A1C >8% (which this patient likely has): Start TDD 0.2-0.3 U/kg
- However, with glucose >300 mg/dL, the higher 0.4-0.5 U/kg range is more appropriate
Titration Strategy
Increase insulin doses every 2-3 days 3, 2:
- If fasting glucose >180 mg/dL: Increase basal by 2 units
- If premeal glucose >110-140 mg/dL: Increase corresponding prandial dose by 10-20%
- Target fasting and premeal glucose <110-140 mg/dL
For hypoglycemia (glucose <70 mg/dL): Reduce corresponding insulin dose by 10-20% 2.
Why Not Higher or Lower?
The "low-dose" approach (insulin-sensitive column starting at 2 units) is reserved for elderly, renally impaired, or NPO patients 1. This patient's severe hyperglycemia demands more aggressive therapy.
The "high-dose" approach (insulin-resistant column) should be reserved for patients on high-dose corticosteroids or requiring >80 units/day pre-admission 1.
The medium-intensity "usual" column represents the evidence-based standard for most hospitalized patients with significant hyperglycemia 1, 4.