What is the recommended decrease in insulin NPH (Neutral Protamine Hagedorn) dose when tapering steroids?

Adjusting NPH Insulin During Steroid Taper

When tapering steroids, NPH insulin should be reduced by 10-20% of the corresponding dose for each reduction in steroid dose to prevent hypoglycemia. 1

Understanding NPH and Steroid Interaction

• NPH insulin is the preferred insulin formulation for managing steroid-induced hyperglycemia because its intermediate-acting profile peaks at 4-6 hours, aligning with the peak hyperglycemic effect of glucocorticoids 1
• Morning administration of NPH insulin is specifically recommended for steroid-induced hyperglycemia to match the pharmacokinetic profile of daily glucocorticoid therapy 1, 2
• The American Diabetes Association recommends considering dosing NPH in the morning specifically for steroid-induced hyperglycemia 2

Specific NPH Reduction Protocol During Steroid Taper

• For each reduction in steroid dose, reduce the corresponding NPH insulin dose by 10-20% 1, 2
• Monitor blood glucose closely during the taper period to guide further adjustments 1
• If hypoglycemia occurs during the taper, determine the cause and if no clear reason is found, further lower the NPH dose by an additional 10-20% 2, 1

Practical Implementation

• For patients on once-daily NPH and steroids, adjust the morning NPH dose proportionally to the steroid reduction 1
• For patients on twice-daily NPH regimen (2/3 morning, 1/3 evening), focus primarily on reducing the morning dose when tapering morning steroids 2, 3
• More aggressive NPH dose reductions may be needed in patients with:
  • Declining renal function 3
  • Lower body weight 4
  • History of hypoglycemia 2

Monitoring During Taper

• Check blood glucose levels more frequently during the steroid taper period, especially before meals and at bedtime 1, 5
• Pay particular attention to midday and afternoon glucose levels, as these are most affected by morning steroid doses 6
• If blood glucose consistently falls below target range, consider a more aggressive NPH reduction of 20-30% 1, 2

Common Pitfalls to Avoid

• Failing to reduce insulin when steroids are tapered, which is a common cause of hypoglycemia 1
• Reducing insulin too aggressively, which can lead to rebound hyperglycemia 4
• Not accounting for the timing of steroid administration when adjusting NPH timing 1, 6
• Overlooking that higher initial NPH:steroid ratios (units of NPH per mg of prednisone equivalent) may require more aggressive NPH reduction during taper 4

Special Considerations

• For patients on high-dose steroids (prednisone >40 mg/day), who typically require 40-60% more insulin than standard dosing, reduction in NPH should be proportionally larger during taper 1, 5
• For patients with type 1 diabetes, maintain some basal insulin coverage even with complete steroid discontinuation to prevent diabetic ketoacidosis 2
• Consider switching from NPH to a long-acting basal analog after complete steroid discontinuation if the patient has frequent hypoglycemia 2