Weight-Based Correctional Insulin Sliding Scale Directions
For a 70 kg adult with finger-stick glucose ≥100 mg/dL, use correctional rapid-acting insulin before meals or every 6 hours if NPO, with dosing based on a correction factor of 1500 divided by total daily insulin dose (TDD), or approximately 1 unit per 50 mg/dL above target if insulin-naive. 1
Initial Assessment and Approach
The appropriateness of sliding scale insulin alone depends critically on the severity of hyperglycemia and prior diabetes treatment:
When Sliding Scale Alone is Appropriate:
- Patients without known diabetes with glucose >140 mg/dL but <180 mg/dL 1
- Patients on diet or oral agents with admission glucose <180 mg/dL 1, 2
- Mild hyperglycemia (<200 mg/dL) in insulin-naive patients 3
Research supports this approach: Among patients with admission glucose <180 mg/dL treated with sliding scale alone, 83-86% achieved target control (70-180 mg/dL) without hypoglycemia 2. However, only 18% with admission glucose ≥250 mg/dL achieved adequate control 2.
When to Add Scheduled Insulin:
Add basal insulin if ≥2 glucose readings ≥180 mg/dL occur within 24 hours on correctional insulin alone 1. This is a critical threshold—do not continue sliding scale monotherapy beyond this point.
Specific Dosing Calculations for 70 kg Patient
Correction Factor Formula:
For a 70 kg patient, calculate as follows:
If insulin-naive or unknown TDD:
- Correction Factor (CF) = 1500 ÷ estimated TDD
- Estimated TDD for 70 kg = 0.3-0.5 units/kg = 21-35 units
- CF = approximately 1 unit per 40-70 mg/dL above target 4
- Practical approach: 1 unit per 50 mg/dL above 150 mg/dL target
If known home insulin dose:
- CF = 1500 ÷ TDD 4
- Example: If home TDD = 30 units, CF = 50 (1 unit per 50 mg/dL)
Dosing Schedule:
- Check glucose before meals and at bedtime (or every 6 hours if NPO)
- Give rapid-acting insulin (lispro, aspart, or glulisine) based on correction factor
- Recent evidence suggests bedtime sliding scale is unnecessary for glucose <300 mg/dL 5—morning glucose actually improved when bedtime insulin was withheld for glucose <300 mg/dL
Critical Pitfalls to Avoid
Do Not Use Sliding Scale Alone For:
- Type 1 diabetes (absolute contraindication—requires basal insulin) 3
- Severe hyperglycemia (>300 mg/dL) 3
- Patients on high-dose home insulin (≥0.6 units/kg/day) 3
- Persistent hyperglycemia (≥2 readings ≥180 mg/dL in 24 hours) 1
Target Range:
Maintain glucose 100-180 mg/dL 1. This is the consensus target for non-critically ill hospitalized patients.
Transition Strategy
If sliding scale fails (persistent hyperglycemia as defined above):
For 70 kg patient transitioning to scheduled insulin:
- Start basal insulin 0.2 units/kg = 14 units daily (for moderate hyperglycemia 200-300 mg/dL) 3
- Continue correction doses with rapid-acting insulin before meals
- For severe hyperglycemia >300 mg/dL, initiate basal-bolus regimen with TDD 0.3 units/kg = 21 units (half basal, half divided as prandial) 3
Important Nuance
The evidence strongly favors basal-bolus over sliding scale alone for glycemic control 3, but sliding scale carries 4-6 times lower hypoglycemia risk 3. Therefore, for patients with mild hyperglycemia (<200 mg/dL), good prior control, or high hypoglycemia risk (elderly, renal failure, poor intake), sliding scale alone is reasonable as initial therapy 3, with close monitoring for the need to escalate.