How to convert Mixtard (biphasic insulin) 30U twice daily to basal-bolus?

Converting Mixtard 30U Twice Daily to Basal-Bolus Insulin

Calculate the total daily dose (60 units from Mixtard 30U BD), then split it as 50% basal insulin (30 units once daily) and 50% rapid-acting prandial insulin (10 units before each of three meals). 1

Step 1: Calculate Total Daily Dose (TDD)

• Your current Mixtard regimen provides 60 units total daily (30 units × 2 doses) 1
• This becomes your starting TDD for the basal-bolus conversion 1

Step 2: Split Into Basal and Bolus Components

Basal insulin (50% of TDD):

• Give 30 units of long-acting insulin (glargine or detemir) once daily at the same time each day 1, 2
• Administer at bedtime or morning, maintaining consistency 2

Prandial insulin (50% of TDD):

• Divide the remaining 30 units equally across three meals: 10 units before breakfast, 10 units before lunch, and 10 units before dinner 1
• Use rapid-acting insulin analogs (aspart, lispro, or glulisine) administered 0-15 minutes before meals 1

Step 3: Titration Strategy

For basal insulin adjustment:

• Increase by 2 units every 3 days if fasting glucose is 140-179 mg/dL 2
• Increase by 4 units every 3 days if fasting glucose ≥180 mg/dL 2
• Target fasting plasma glucose: 80-130 mg/dL 1, 2

For prandial insulin adjustment:

• Adjust each meal dose by 1-2 units or 10-15% every 3 days based on pre-meal and 2-hour postprandial glucose readings 1
• If hypoglycemia occurs, reduce the corresponding insulin dose by 10-20% 1

Critical Considerations

Watch for overbasalization:

• If basal insulin exceeds 0.5 units/kg/day (approximately 35-40 units for a 70 kg patient) without achieving targets, intensify prandial insulin rather than continuing to escalate basal doses 1, 2
• Clinical signals include bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, and high glucose variability 1

Maintain foundation therapy:

• Continue metformin unless contraindicated, as it reduces total insulin requirements and provides complementary glucose-lowering effects 2

Monitor closely:

• Daily fasting blood glucose monitoring is essential during the first 2-4 weeks of titration 1, 2
• Check HbA1c every 3 months during intensive titration 2

Common Pitfalls to Avoid

• Do not use the 50-50 split rigidly long-term - while this is the appropriate starting point, individual patients may require different ratios (some need <40% basal, others >60%) based on their glucose patterns 3
• Do not delay prandial insulin adjustments - each meal dose should be titrated independently based on its corresponding postprandial glucose response 1
• Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia, as this leads to increased hypoglycemia risk 1, 2