NPH Insulin Dosing Adjustment for Increased Methylprednisolone
Increase the morning NPH dose to approximately 38-48 units when methylprednisolone is doubled from 62.5 mg to 125 mg, representing a 60% increase in insulin to match the doubled steroid dose.
Rationale for Dose Escalation
High-dose glucocorticoids require 40-60% more insulin than standard dosing, and since you are doubling the methylprednisolone dose (from 62.5 mg to 125 mg), the NPH insulin should be increased proportionally 1
The current morning dose of 24 units maintained stable blood glucose on 62.5 mg methylprednisolone, so doubling the steroid necessitates approximately doubling the insulin coverage 1
A 60% increase (24 units × 1.6 = 38 units) represents a conservative starting point, while a full doubling (48 units) may be needed for complete coverage 1
Specific Dosing Algorithm
Start with 40 units NPH this morning as a middle-ground approach between the 60% increase (38 units) and full doubling (48 units) 1
Morning administration of NPH insulin is specifically recommended for steroid-induced hyperglycemia to match the pharmacokinetic profile of daily glucocorticoid therapy, as methylprednisolone causes hyperglycemia predominantly between midday and midnight 1, 2
The evening NPH dose (currently 22 units) should also be increased proportionally to approximately 35-44 units, though the morning dose takes priority since that's when the steroid is administered 1
Monitoring and Titration Protocol
Check blood glucose every 2-4 hours for the first 24-48 hours after this dose adjustment to identify patterns of hyper- or hypoglycemia 1
If fasting glucose remains elevated above 130 mg/dL after 3 days, increase NPH by 2 units every 3 days until target is achieved 1
If hypoglycemia occurs (glucose <70 mg/dL), immediately reduce the corresponding insulin dose by 10-20% without waiting 1
Target fasting glucose <130 mg/dL and daytime glucose 140-180 mg/dL 1
Critical Safety Considerations
The initial insulin dose of 0.5 units/kg bodyweight is recommended for steroid-induced hyperglycemia, and patients often require greater than 30% increases in insulin dose when steroids are escalated 2
Watch for the "midday to midnight" hyperglycemia pattern characteristic of methylprednisolone—if this persists despite dose adjustments, consider splitting NPH to twice daily (2/3 morning, 1/3 evening) 1
Methylprednisolone pulses produce significant increases in fasting glucose in most patients, with prevalence of hyperglycemia reaching 98% after three consecutive days 3
Common Pitfalls to Avoid
Do not use the same NPH dose when doubling the steroid—this is the most common error and will result in severe hyperglycemia 1
Avoid waiting too long to uptitrate; aggressive initial dosing adjustments are appropriate when steroids are significantly increased 2
If glycemic control remains suboptimal with once-daily morning NPH, consider splitting the dose rather than continuing to increase the single morning dose 1