Mixtard 30/70 Dosing for Conversion from Basal-Bolus Regimen
Calculate Total Daily Insulin Dose
The patient's current total daily insulin dose is 42 units (12 units glargine + 4 units morning Actrapid + 12 units lunch Actrapid + 14 units dinner Actrapid) 1.
Apply the Conversion Algorithm
When converting from a basal-bolus regimen to Mixtard 30/70, use 80% of the current total daily dose and distribute it as 2/3 before breakfast and 1/3 before dinner 2. This reduction accounts for the different pharmacokinetic profile and helps prevent hypoglycemia during the transition 2.
Specific Dosing Calculation:
- Total Mixtard 30/70 daily dose: 42 units × 0.80 = 33.6 units (round to 34 units) 2
- Morning dose (before breakfast): 34 units × 2/3 = 22-23 units 2
- Evening dose (before dinner): 34 units × 1/3 = 11-12 units 2
Physiologic Rationale
The larger morning dose addresses higher daytime insulin requirements when counter-regulatory hormones increase insulin resistance 3. The morning injection provides both basal coverage throughout the day and prandial coverage for breakfast and lunch, while the evening dose covers overnight basal needs and dinner 2.
Titration Strategy After Initiation
Adjust the morning dose based on pre-dinner and bedtime glucose readings, and adjust the evening dose based on fasting glucose readings 2. Increase by 2 units every 3 days to reach target fasting plasma glucose of 80-130 mg/dL without hypoglycemia 2, 1. If hypoglycemia occurs without clear cause, reduce the corresponding dose by 10-20% 2, 1.
Critical Monitoring Points
- Target fasting glucose: 80-130 mg/dL 1
- Titrate systematically every 3 days based on glucose patterns rather than waiting weeks between changes 2
- Monitor for overbasalization if total insulin dose exceeds 0.5 units/kg/day (approximately 35-40 units for a 70 kg patient) with persistent hyperglycemia 2, 1
Important Considerations
Continue metformin unless contraindicated, as this combination provides superior glycemic control with reduced insulin requirements and less weight gain 1. Consider discontinuing sulfonylureas when starting premixed insulin to reduce hypoglycemia risk 1.
Rotate injection sites systematically within one area to minimize absorption variability 3.
When to Advance Beyond Twice-Daily Mixtard
If HbA1c remains above target after optimizing the twice-daily regimen (typically after 3-6 months), consider transitioning back to a basal-bolus regimen with separate basal and prandial insulins for more flexible dosing 2, 1.