NPH Insulin Dosing for Steroid-Induced Hyperglycemia in an Elderly Patient
Start NPH insulin at 7-14 units administered once daily in the morning, calculated as 0.1-0.2 units/kg body weight, and titrate upward by 2 units every 3 days based on fasting glucose monitoring. 1
Initial Dosing Strategy
For this elderly male patient with obesity, impaired renal function, and newly started prednisone, the recommended approach prioritizes safety while addressing steroid-induced hyperglycemia:
Begin with 0.1-0.2 units/kg per day of NPH insulin administered in the morning (approximately 7-14 units for a 68 kg patient), as this aligns with the pharmacokinetic profile of daily glucocorticoid therapy 1, 2
Administer NPH in the morning specifically to match the peak hyperglycemic effect of glucocorticoids, which occurs 4-6 hours after NPH administration 1
For patients on high-dose glucocorticoids, anticipate 40-60% higher insulin requirements than standard dosing, so consider starting at the higher end of the range 1
Managing Concurrent Lantus Therapy
Since this patient is already taking Lantus (insulin glargine):
Reduce the current Lantus dose by 20% when initiating NPH to prevent hypoglycemia, as the NPH will provide additional basal coverage during daytime hours when steroids exert their peak effect 1
Continue a reduced dose of Lantus at bedtime to maintain overnight basal coverage, as NPH given in the morning may not provide adequate 24-hour coverage 1
Alternatively, consider using 70% of the total current basal insulin dose as morning NPH only if simplifying to a single basal insulin regimen 3
Special Considerations for This Patient's Comorbidities
Impaired Renal Function
Patients with impaired renal function have increased hypoglycemia risk due to decreased insulin clearance and impaired renal gluconeogenesis 2
Morning NPH administration allows better monitoring during waking hours and reduces risk of undetected nocturnal hypoglycemia, which is particularly important in renal impairment 2
Consider starting at the lower end of the dosing range (0.1 units/kg) and reduce by an additional 10-20% if the patient has significant renal impairment 2
Elderly Status
Once-daily basal insulin injection therapy is associated with minimal side effects and may be reasonable in elderly patients 1
Assess visual and motor skills and cognitive ability before initiating therapy, as insulin administration requires these capabilities 1
Set more conservative glycemic targets (fasting 90-150 mg/dL rather than <130 mg/dL) to minimize hypoglycemia risk in elderly patients 3
Titration Protocol
Target fasting glucose of 90-150 mg/dL, adjusting based on overall health status 3, 1
If 50% of fasting fingerstick values over one week are above goal, increase NPH by 2 units 3
If more than 2 fasting values per week are <80 mg/dL, decrease NPH by 2 units 3
For persistent hyperglycemia, increase by 2 units every 3 days until target glucose is achieved without hypoglycemia 1, 2
If hypoglycemia occurs without clear cause, reduce the NPH dose by 10-20% immediately 1, 2
Monitoring Requirements
Check blood glucose every 2-4 hours for the first 24-48 hours after initiating or adjusting NPH to identify patterns of hyper- or hypoglycemia 1
Monitor fasting fingerstick glucose daily during titration phase 3
Watch for the "midday to midnight" hyperglycemia pattern characteristic of prednisone—if this persists despite dose adjustments, consider splitting NPH to twice daily (2/3 morning, 1/3 evening) 1
Critical Pitfalls to Avoid
Do not discontinue basal insulin even if the patient becomes NPO—reduce the dose but maintain some coverage, especially given the steroid therapy 1
Avoid bedtime NPH in patients with impaired renal function due to increased risk of undetected nocturnal hypoglycemia 2
Do not use rapid- or short-acting insulin at bedtime during this regimen 3
Be aware that insulin requirements may fluctuate with changes in renal function, requiring more frequent monitoring and dose adjustments 2