What should the NPH (Neutral Protamine Hagedorn) insulin dose be for a patient with type 2 diabetes, currently taking prednisolone (20mg reducing to 15mg) and NPH insulin 22 units with a carbohydrate ratio of 1:6, who wants to discontinue mealtime insulin?

NPH Insulin Dosing During Steroid Taper Without Mealtime Insulin

Increase your NPH insulin to approximately 28-30 units given as a single morning dose and discontinue your mealtime insulin, then reduce the NPH by 10-20% (to 22-24 units) when you complete the taper from prednisone 20mg to 15mg. 1

Initial NPH Dose Calculation

Your current regimen includes NPH 22 units plus mealtime insulin at a 1:6 carb ratio. To eliminate mealtime insulin while maintaining glycemic control:

• Start with NPH 28-30 units given in the morning to cover both basal needs and the carbohydrate load previously managed by mealtime insulin 1
• This represents approximately a 27-36% increase from your current NPH dose, accounting for the removal of prandial coverage 1
• Morning administration is specifically recommended for steroid-induced hyperglycemia because NPH peaks at 4-6 hours, matching the midday-to-midnight hyperglycemia pattern caused by prednisone 1, 2

Dose Adjustment During Steroid Taper

When reducing prednisone from 20mg to 15mg (a 25% reduction):

• Reduce NPH by 10-20% to prevent hypoglycemia - this means decreasing from 28-30 units down to 22-24 units 1
• The 10-20% reduction guideline is specifically designed for steroid tapers to match the decreased insulin resistance 1
• Make this adjustment on the same day you reduce the prednisone dose 1

Monitoring Protocol

• Check blood glucose every 2-4 hours for the first 24-48 hours after making dose changes to identify patterns 1
• Target fasting glucose <130 mg/dL and daytime glucose 140-180 mg/dL 1
• If fasting glucose remains >130 mg/dL after 3 days, increase NPH by 2 units every 3 days 1
• If hypoglycemia occurs (glucose <70 mg/dL), immediately reduce NPH by an additional 10-20% without waiting 1

Critical Pitfalls to Avoid

• Do not give NPH at bedtime - this will cause nocturnal hypoglycemia while undertreating daytime steroid-induced hyperglycemia 1, 2
• Watch for the characteristic "midday to midnight" hyperglycemia pattern from prednisone - if this persists despite dose adjustments, consider splitting NPH to twice daily (2/3 morning, 1/3 evening) 1
• If you experience hypoglycemia during the steroid taper, reduce the NPH dose further by 10-20% rather than reintroducing mealtime insulin 1

Alternative Approach if Single-Dose NPH Fails

If glycemic control remains suboptimal with once-daily morning NPH:

• Split the total NPH dose as 2/3 in the morning and 1/3 before dinner 1
• This provides better coverage for the extended hyperglycemic effect of steroids while maintaining freedom from mealtime injections 1