Insulin Dose Calculation for RBS 220 mg/dL - 56-Year-Old Female

Important clinical note: This is a general framework. The actual dose must always be individualized based on the patient's weight, total daily insulin dose, renal/hepatic function, oral intake, and whether she is insulin-naive or already on insulin. Always consult a physician before administering insulin.

Step 1 - Determine the Context

Step 2 - Correction (Supplemental) Dose

Correction Dose (units) = (Actual BG - Target BG) ÷ Correction Factor (ISF)

• If TDI is unknown, a reasonable default ISF for a Type 2 diabetic adult is 40-50 mg/dL per unit

• Actual BG = 220 mg/dL
• Target BG = 120 mg/dL (common inpatient target)
• ISF = 50 mg/dL per unit (assumed)

Correction dose = (220 - 120) ÷ 50 = 100 ÷ 50 = 2 units rapid-acting insulin

Step 3 - Weight-Based Starting Dose (If Insulin-Naive)

• Basal insulin (long-acting, e.g., glargine or NPH): 0.1-0.2 units/kg/day
• Premeal (bolus) insulin (rapid-acting, e.g., lispro, aspart): 0.1-0.2 units/kg/day divided by 3 meals
• Correction dose: 1-2 units per 50 mg/dL above 140 mg/dL

• Basal insulin: 6-12 units of long-acting insulin once daily
• Premeal insulin: 2-4 units rapid-acting before each meal
• Correction for RBS 220: +2 units rapid-acting (as calculated above)

Step 4 - Sliding Scale Reference (Hospitalized Patients)

• At RBS 220, the sliding scale gives 4 units as a standalone correction.
• Note: Sliding scale alone (without basal insulin) is considered inferior to a basal-bolus regimen for sustained glycemic control.

Key Clinical Caveats for This Patient

1. Age 56, female - No specific age-based dose adjustment needed at this age, but assess for renal function (reduced renal clearance prolongs insulin action) and risk of hypoglycemia.
2. Not eating / fasting - Give correction dose only; do NOT give mealtime insulin if she is not taking oral feeds.
3. Type 1 vs Type 2 - If T1DM, do not skip basal insulin even if fasting. If T2DM, correction alone may be sufficient for mild elevation (220 mg/dL).
4. Avoid bedtime correction for mild hyperglycemia (RBS 220 is not alarming enough to warrant a nighttime correction dose, which risks nocturnal hypoglycemia).
5. Recheck BG 2 hours after correction to assess response.

Summary

• Correction dose: ~2 units rapid-acting insulin (using correction factor of 50, target 120)
• Sliding scale equivalent: 4 units (institutional moderate scale)
• If insulin-naive and starting therapy: 6-12 units basal (long-acting) + 2-4 units premeal + 2-unit correction
• Always pair with a long-acting basal insulin for sustained control - correction/sliding scale alone is not adequate long-term