What is the correction factor for a patient on Humulin N (NPH insulin) with a total daily dose (TDD) of 36 units?

Correction Factor for a Patient on Humulin N with TDD of 36 Units

For a patient with a total daily dose (TDD) of 36 units of Humulin N (NPH insulin), the appropriate correction factor is 1800 ÷ 36 = 50 mg/dL per unit of insulin. 1

Understanding Correction Factor Calculation

The correction factor (also known as insulin sensitivity factor) is calculated using the "1800 rule" for regular insulin:

• Correction Factor = 1800 ÷ Total Daily Dose 1
• For this patient: 1800 ÷ 36 = 50 mg/dL per unit 1

This means each unit of correction insulin will lower blood glucose by approximately 50 mg/dL.

Important Considerations for NPH Insulin

• NPH insulin (Humulin N) has an intermediate duration of action with:

  • Onset: 1-2 hours 2
  • Peak effect: 5-11 hours 2
  • Total duration: 20-25 hours 3, 2

• NPH insulin requires careful timing due to its peak action profile, which differs from basal analogs 1

• When using NPH as the basal insulin, consider:

  • Typically administered once or twice daily 1
  • Higher risk of hypoglycemia compared to long-acting analogs 1, 4
  • May need to be split into morning and evening doses for better coverage 1

Implementing Correction Doses with NPH

When implementing correction doses for a patient on NPH insulin:

• Use rapid-acting insulin for corrections rather than additional NPH 1
• Be cautious of stacking insulin, especially when NPH is at peak effect (5-11 hours post-injection) 2
• Consider the timing of NPH administration when calculating correction doses 1

Monitoring and Adjusting

• Monitor for hypoglycemia, especially during NPH peak action times 4
• Consider reducing correction doses by 10-20% if hypoglycemia occurs 1
• Evaluate the adequacy of the basal NPH dose regularly 1
• If frequent corrections are needed, consider adjusting the NPH regimen rather than relying on multiple corrections 1

Common Pitfalls to Avoid

• Avoid using sliding scale insulin alone as the primary strategy for glycemic control 1
• Be aware that NPH has a more pronounced peak than long-acting analogs, increasing hypoglycemia risk 4
• Don't overlook the need to potentially split NPH doses for better 24-hour coverage 1, 3
• Remember that correction factors may need adjustment based on time of day due to varying insulin sensitivity 1

For optimal glycemic control, a basal-bolus approach is generally more effective than relying solely on correction doses, particularly for patients using NPH insulin as their basal insulin 1.