What is the recommended dose and timing of human Actrapid (fast-acting insulin) for an adult patient with diabetes, previously on Mixtard (biphasic insulin)?

Actrapid (Regular Human Insulin) Dosing and Timing

Critical Timing Requirement for Actrapid

Actrapid (regular human insulin) must be injected 30 minutes before meals to achieve optimal postprandial glucose control, unlike rapid-acting insulin analogs which can be given 0-15 minutes before eating. 1, 2

Transitioning from Mixtard to Basal-Bolus Therapy

Calculate Total Daily Dose (TDD)

• Add up all current Mixtard doses to determine your baseline TDD 3
• For patients with severe hyperglycemia (A1C ≥9%), consider starting with 0.3-0.5 units/kg/day as TDD 3, 4
• For metabolically stable patients, 0.5 units/kg/day is typical 3

Split Between Basal and Prandial Insulin

• Divide TDD as 50% basal insulin (long-acting) and 50% prandial insulin (Actrapid) 3, 4
• Distribute the prandial 50% equally among three meals (approximately 17% of TDD per meal) 3

Actrapid Administration Protocol

Injection Timing

• Inject Actrapid 30 minutes before meal ingestion 2
• This 30-minute interval is essential because regular insulin has a slower onset of action compared to rapid-acting analogs 1, 2
• Surveys show 75% of patients use intervals <30 minutes, but optimal control requires the full 30-minute wait 2

Dosing Strategy

• Start with calculated meal dose (approximately 17% of TDD per meal) 3
• For patients not counting carbohydrates, use a stepped correction approach: add 2 units if pre-meal glucose >250 mg/dL, add 4 units if >350 mg/dL 3
• For carbohydrate counting, use insulin-to-carbohydrate ratio of 1 unit per 10-15 grams initially 3

Titration Schedule

Adjusting Actrapid Doses

• Increase prandial Actrapid by 1-2 units or 10-15% every 3 days based on 2-hour postprandial glucose readings 3
• Target postprandial glucose <180 mg/dL 3, 5
• If hypoglycemia occurs, reduce the corresponding dose by 10-20% immediately 3

Monitoring Requirements

• Check pre-meal glucose before each Actrapid injection 3
• Check 2-hour postprandial glucose to assess meal coverage adequacy 3
• Daily monitoring is essential during titration phase 3

Critical Pitfalls to Avoid

Timing Errors

• Never inject Actrapid immediately before or after meals - this timing is only appropriate for rapid-acting analogs like lispro or aspart, not regular insulin 1, 6, 5
• Do not inject Actrapid at bedtime due to increased nocturnal hypoglycemia risk 3

Dosing Mistakes

• Do not use Actrapid as monotherapy with sliding scale only - this leads to dangerous glucose fluctuations 3, 7
• Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day without adequate prandial coverage 3

Medication Management

• Continue metformin unless contraindicated when using insulin therapy 3, 4
• Do not abruptly discontinue oral medications when starting insulin 7

Special Considerations

Hyperglycemic Patients

• In hyperglycemic patients (glucose >250 mg/dL), injecting Actrapid 15-30 minutes before meals significantly improves postprandial glucose control compared to injection at mealtime 6
• However, 30-minute pre-meal injection may cause late postprandial hypoglycemia in some patients, so 15-minute interval may be safer 6

Mixing Considerations

• Actrapid (short-acting insulin) should not be mixed with lente insulins due to zinc binding that delays onset 1
• Can be mixed with NPH insulin if needed, though separate injections are preferred 1
• Never mix any insulin with insulin glargine 1, 3