Dosing Regimen for Type 1 Diabetes on 70/30 Insulin
For patients with type 1 diabetes, a basal-bolus insulin regimen is strongly recommended over premixed 70/30 (NPH/regular) insulin due to significantly increased risk of hypoglycemia with premixed insulin formulations. 1
Why Basal-Bolus is Preferred for Type 1 Diabetes
- Guidelines from the American Diabetes Association consistently recommend against premixed insulin regimens for patients with type 1 diabetes 1
- A randomized inpatient study comparing 70/30 NPH/regular insulin versus basal-bolus therapy showed comparable glycemic control but significantly increased hypoglycemia in the premixed insulin group 1
- For type 1 diabetes, dosing insulin based solely on premeal glucose levels (as with premixed insulin) does not account for basal insulin requirements or caloric intake, increasing both hypoglycemia and hyperglycemia risks 1
If 70/30 Insulin Must Be Used (Despite Recommendations Against It)
If a patient with type 1 diabetes must use 70/30 insulin due to access, cost, or other constraints:
Dosing Schedule
- Twice-daily administration is typically required
- Morning dose: Before breakfast
- Evening dose: Before dinner
- Total daily dose: Usually 0.5-0.7 units/kg/day, divided between morning and evening doses 2
Dose Distribution
- Morning dose: Usually higher (approximately 60-70% of total daily dose)
- Evening dose: Usually lower (approximately 30-40% of total daily dose) 1
- Example: For a 70kg patient requiring 0.6 units/kg/day (42 units total)
- Morning dose: 25-30 units
- Evening dose: 12-17 units
Timing of Administration
- Regular insulin component requires administration 30 minutes before meals 3
- This timing is critical to match insulin action with food absorption
Blood Glucose Monitoring Requirements
More intensive monitoring is required with premixed insulin:
- Pre-breakfast and pre-dinner (essential)
- 2 hours post-breakfast and post-dinner (to assess postprandial control)
- Bedtime and occasional 3 AM readings (to detect nocturnal hypoglycemia)
- During illness or significant changes in routine
Adjustments and Considerations
- Dose adjustments should be made cautiously, typically 10-15% at a time
- Morning dose affects:
- Daytime glucose levels
- Pre-dinner glucose
- Evening dose affects:
- Overnight glucose levels
- Pre-breakfast glucose
Important Cautions and Limitations
- Fixed ratio of 70/30 severely limits flexibility in dosing
- Cannot independently adjust basal and bolus components
- High risk of hypoglycemia, especially nocturnal
- Requires consistent meal timing, content, and carbohydrate amounts
- Exercise and activity must be carefully planned
- Not suitable for patients with variable schedules or eating patterns
Transition to Preferred Regimen
Ideally, patients with type 1 diabetes should transition to a basal-bolus regimen consisting of:
- Once or twice daily long-acting insulin (glargine, detemir, degludec)
- Rapid-acting insulin before meals
- This regimen allows for greater flexibility, better glycemic control, and reduced hypoglycemia risk 4
Remember that premixed insulin regimens are not routinely recommended for patients with type 1 diabetes due to the significantly increased risk of hypoglycemia and limited flexibility in dosing. A basal-bolus insulin regimen is strongly preferred for this population.