Insulin Mixtard Dosing Recommendations
The recommended dosage of Insulin Mixtard (Biphasic Isophane Insulin) is to start with a total daily dose calculated as 80% of the current NPH insulin dose, divided into two daily injections with 2/3 given before breakfast and 1/3 given before dinner.
Initial Dosing
- For insulin-naive patients with type 2 diabetes, start with 10 units per day or 0.1-0.2 units/kg/day 1
- For patients switching from NPH insulin to Mixtard (70/30 premixed insulin), calculate the total daily dose as 80% of the current NPH insulin total daily dose 2
- Divide the total daily dose into two injections: 2/3 before breakfast and 1/3 before dinner 2, 1
Titration and Adjustment
- Increase dose by 10-15%, or 2-4 units, once or twice weekly until fasting blood glucose target is met 1
- Target fasting glucose values should be between 4.0-7.0 mmol/L (72-126 mg/dL) 2
- Monitor both fasting and postprandial glucose levels to assess the effectiveness of the regimen 2
- Check blood glucose more frequently during the transition period when switching from NPH to Mixtard 2
Clinical Considerations
- Mixtard 50 HM (50% regular insulin/50% NPH) may be more appropriate for patients with post-breakfast hyperglycemia compared to Mixtard 30 HM (30% regular insulin/70% NPH) 3
- Morning doses may need to be higher than evening doses (ratio approximately 55:45 to 60:40) for optimal glycemic control 4
- Consider reducing the dose if A1C is <8% when switching to avoid hypoglycemia 2
Special Populations
- For patients with type 1 diabetes, the typical starting dose is 0.5 units/kg/day with half administered as prandial insulin and half as basal insulin 1
- In children and adolescents with type 1 diabetes, Mixtard 30 HM has been shown to improve glycemic control when administered twice daily 5
Advantages and Limitations
- Premixed insulin provides both basal and prandial coverage with fewer daily injections, simplifying the regimen compared to separate basal and bolus injections 2
- However, premixed insulin has less flexibility in dosing compared to basal-bolus regimens 2
- Consistent meal timing is important with premixed insulin regimens 2
Common Pitfalls to Avoid
- Converting on a 1:1 basis when switching from NPH to Mixtard (use 80% of NPH dose instead) 2
- Using the same dose for both morning and evening injections (use 2/3 morning, 1/3 evening) 2
- Neglecting monitoring during transition period 2
- Forgetting about meal timing, which is more critical with premixed insulins 2