How do I convert a patient taking Mixtard (insulin) 30 units in the morning and 35 units in the evening to a basal-bolus regimen?

Converting Mixtard 30/35 Units to Basal-Bolus Insulin Regimen

Calculate the total daily dose (65 units) and split it 50% basal insulin (approximately 30-35 units of long-acting insulin once daily) and 50% prandial insulin (approximately 10-12 units of rapid-acting insulin before each of three meals), then titrate based on glucose monitoring. 1

Step 1: Calculate Total Daily Dose and Initial Split

Current total daily insulin dose = 30 + 35 = 65 units total 1

For conversion from premixed insulin to basal-bolus therapy:

• Give 50% as basal insulin (long-acting): 32-33 units once daily 1
• Give 50% as prandial insulin (rapid-acting): Divide remaining 32-33 units among three meals = approximately 10-11 units before each meal 1

The American Diabetes Association recommends this 50:50 split when transitioning from premixed insulin regimens to basal-bolus therapy 1. Randomized trials demonstrate that basal-bolus therapy provides superior glycemic control with reduced hospital complications compared to premixed insulin regimens 1.

Step 2: Select Specific Insulin Products

Basal insulin options:

• Insulin glargine (Lantus/Basaglar): 32-33 units once daily, typically in evening 1
• Insulin detemir: May require 38% higher total daily dose than glargine (approximately 44-46 units), often split twice daily 1
• Insulin degludec (Tresiba): 32-33 units once daily 2

Prandial insulin:

• Rapid-acting analog (insulin aspart/lispro/glulisine): 10-11 units before each of three meals 1, 3

Step 3: Titration Protocol

Basal Insulin Titration:

• Target fasting glucose: 80-130 mg/dL 1, 3
• If fasting glucose 140-179 mg/dL: Increase basal insulin by 2 units every 3 days 1, 3
• If fasting glucose ≥180 mg/dL: Increase basal insulin by 4 units every 3 days 1, 3
• If hypoglycemia occurs: Reduce dose by 10-20% immediately 1, 3

Prandial Insulin Titration:

• Target 2-hour postprandial glucose: <180 mg/dL 3, 2
• Increase each meal's dose by 1-2 units or 10-15% every 3 days based on 2-hour postprandial glucose readings 1, 3, 2
• Adjust each meal dose independently based on glucose 2 hours after that specific meal 3

Step 4: Monitoring Requirements

Essential glucose checks:

• Fasting glucose every morning to guide basal insulin adjustments 1, 3
• Pre-meal glucose before each meal to assess basal insulin adequacy 3, 2
• 2-hour postprandial glucose after meals to guide prandial insulin titration 3, 2

Step 5: Critical Threshold Warning

Watch for overbasalization when basal insulin exceeds 0.5 units/kg/day (approximately 35-40 units for a 70-80 kg patient) 1, 4. Clinical signals include:

• Basal dose >0.5 units/kg/day 1
• Bedtime-to-morning glucose differential ≥50 mg/dL 1
• Hypoglycemia episodes 1
• High glucose variability 1

When basal insulin approaches 0.5-1.0 units/kg/day without achieving glycemic targets, intensify prandial insulin rather than continuing to escalate basal insulin alone 1, 4.

Step 6: Medication Management

Continue metformin unless contraindicated when initiating basal-bolus therapy, as this combination provides superior glycemic control with reduced insulin requirements and less weight gain 1. Consider discontinuing sulfonylureas when advancing to basal-bolus insulin to prevent hypoglycemia 1.

Common Pitfalls to Avoid

• Never continue premixed insulin (Mixtard) in patients transitioning to basal-bolus therapy, as randomized trials show significantly increased hypoglycemia rates with premixed regimens 1
• Never delay insulin intensification in patients not achieving glycemic goals, as this prolongs hyperglycemia exposure and increases complication risk 1
• Never use sliding scale insulin as monotherapy during the transition, as this leads to dangerous glucose fluctuations 1, 2
• Never give rapid-acting insulin at bedtime to avoid nocturnal hypoglycemia risk 1, 2

Patient Education Essentials

Provide comprehensive education on:

• Proper insulin injection technique with 90-degree angle and systematic site rotation 2
• Recognition and treatment of hypoglycemia with 15 grams of fast-acting carbohydrate 1, 3
• Self-monitoring of blood glucose technique 1, 2
• "Sick day" management rules 1
• Insulin storage and handling 1

Expected Timeline and Outcomes

• Fasting glucose should reach 80-130 mg/dL within 2-4 weeks of basal insulin titration 2
• Postprandial glucose should improve to <180 mg/dL within 4-6 weeks of prandial insulin optimization 2
• HbA1c should decrease by 1-2% within 3 months with optimized basal-bolus therapy 2
• Total daily insulin requirements will likely stabilize at 0.5-1.0 units/kg/day once proper distribution is achieved 2