How should the insulin regimen be adjusted for a patient with hyperglycemia on NPH insulin?

Management of Hyperglycemia in a Patient on NPH Insulin

The patient's NPH insulin regimen should be adjusted by adding a rapid-acting insulin analog as a correction dose of 8 units immediately for the current high blood glucose (400 mg/dL), and splitting the NPH dose with ⅔ in the morning and ⅓ in the evening to provide better 24-hour coverage. 1

Assessment of Current Situation

This patient presents with significant hyperglycemia (400 mg/dL) at 5 pm, 8 hours after receiving NPH insulin and 2 hours after eating. This pattern suggests:

1. Inadequate insulin coverage: The patient's single morning dose of NPH insulin (24 units at 9 am) is not providing adequate coverage throughout the day.
2. Post-prandial hyperglycemia: The timing (2 hours after eating) indicates this is likely post-prandial hyperglycemia.

Immediate Management

1. Administer correction dose:
   • Give 8 units of rapid-acting insulin analog immediately for blood glucose >300 mg/dL 1
   • Monitor blood glucose in 2 hours to ensure appropriate response

Insulin Regimen Adjustment

Short-term Adjustments

1. Split the NPH dose 2, 1:

   • Convert to twice-daily NPH insulin
   • Morning dose: ⅔ of total daily NPH dose (approximately 16 units)
   • Evening dose: ⅓ of total daily NPH dose (approximately 8 units)

2. Add prandial insulin coverage 2:

   • Add rapid-acting insulin before meals, starting with 4 units or 10% of the basal insulin dose
   • Titrate based on post-prandial glucose readings

Long-term Insulin Optimization

1. Adjust NPH timing to match needs 2, 1:

   • NPH has a peak action at 4-6 hours after administration
   • Morning dose helps with daytime/lunch coverage
   • Evening dose helps with dinner/overnight coverage

2. Consider a self-mixed/split insulin plan 2:

   • Total NPH dose = 80% of current dose (approximately 19 units)
   • Add short/rapid-acting insulin to each injection (approximately 4 units)

Monitoring and Further Adjustments

1. Blood glucose monitoring schedule:

   • Pre-meal and 2 hours post-meal
   • Bedtime and overnight (3 am) periodically to check for nocturnal hypoglycemia

2. Titration algorithm 2, 1:

   • Increase prandial insulin by 1-2 units or 10-15% if post-prandial glucose remains elevated
   • For hypoglycemia, determine cause and reduce corresponding dose by 10-20%

3. Assess adequacy of insulin dose at each visit 2:

   • Look for patterns of hyperglycemia or hypoglycemia
   • Evaluate for overbasalization (elevated bedtime-to-morning differential)

Special Considerations

1. Meal timing coordination 2:

   • Ensure coordination between meal delivery and insulin administration
   • Consider carbohydrate counting if appropriate for the patient

2. Potential causes of afternoon hyperglycemia:

   • NPH peak action has waned by afternoon (administered at 9 am)
   • Post-prandial glucose excursions typically peak 72±23 minutes after meals 3
   • Potential steroid use (which causes predominantly afternoon/evening hyperglycemia) 2, 1

Common Pitfalls to Avoid

1. Relying solely on fasting glucose: Post-prandial hyperglycemia is common even in patients with apparently good fasting control 4

2. Inadequate dose adjustments: Starting with small increments (2 units) may not be sufficient for significant hyperglycemia

3. Missing the pattern: This afternoon hyperglycemia suggests the need for either additional NPH coverage or prandial insulin with lunch

4. Nocturnal hypoglycemia risk: Adding evening NPH requires monitoring for overnight hypoglycemia

By implementing these adjustments, the patient's glycemic control should improve with better coverage throughout the day, particularly during the afternoon when the current regimen is failing to provide adequate control.