What adjustments should be made to the NPH dose and carb ratio, and what sliding scale regimen is recommended for a patient with hyperglycemia on prednisone and NPH insulin?

Management of Steroid-Induced Hyperglycemia with NPH Insulin

For a patient with blood glucose of 306 mg/dL on prednisone 60 mg with current NPH dose of 10 units and carb ratio of 1:15, the NPH dose should be increased to 30 units daily (0.3 units/kg) and the carb ratio should be adjusted to 1:10, with a sliding scale of 1 unit for every 50 mg/dL above 150 mg/dL. 1

NPH Insulin Adjustment

• For steroid-induced hyperglycemia, NPH insulin is the preferred insulin formulation due to its intermediate-acting profile that peaks at 4-6 hours, aligning with the peak hyperglycemic effect of glucocorticoids 1
• The current dose of 10 units is insufficient for a 97.8 kg patient on high-dose prednisone (60 mg) 1
• Initial NPH insulin dosing should be 0.3 units/kg per day for patients on high-dose glucocorticoids, which for a patient weighing 97.8 kg equals approximately 30 units 1, 2
• Morning administration of NPH insulin is specifically recommended to match the pharmacokinetic profile of daily glucocorticoid therapy 1

Carbohydrate Ratio Adjustment

• The current carb ratio of 1:15 is too conservative for a patient with significant steroid-induced hyperglycemia 1
• Adjust the carbohydrate ratio from 1:15 to 1:10 to provide more insulin coverage for meals 2
• This adjustment accounts for the insulin resistance caused by high-dose prednisone therapy 2

Recommended Sliding Scale

• Implement a sliding scale starting at 150 mg/dL 2, 1:
  • 150-200 mg/dL: add 1 unit
  • 201-250 mg/dL: add 2 units
  • 251-300 mg/dL: add 3 units
  • 301-350 mg/dL: add 4 units

  • 350 mg/dL: add 5 units and contact provider 2

Monitoring and Further Adjustments

• Monitor blood glucose before meals and at bedtime to assess the adequacy of the NPH dose and carb ratio 1
• If hypoglycemia occurs, determine the cause; if no clear reason is found, lower the NPH dose by 10-20% 2, 3
• For persistent hyperglycemia, consider increasing the NPH dose by 2 units every 3 days until target blood glucose is achieved 2
• Consider splitting the NPH dose (2/3 morning, 1/3 evening) if daytime hyperglycemia persists despite dose adjustments 1, 2

Special Considerations for This Patient

• With a BMI of 31, this patient likely has baseline insulin resistance, requiring higher insulin doses 1
• The current NPH dose of 10 units (approximately 0.1 units/kg) is at the lowest end of the recommended starting range and insufficient for steroid-induced hyperglycemia 2, 1
• Research shows that patients on high-dose glucocorticoids may require 40-60% more insulin than standard dosing 1, 4
• NPH insulin has been shown to be more effective than glargine for steroid-induced hyperglycemia, with potentially lower total daily insulin requirements 4

Common Pitfalls to Avoid

• Avoid bedtime NPH in patients with steroid-induced hyperglycemia as the peak action may cause nocturnal hypoglycemia 1, 3
• Do not underestimate insulin requirements in patients on high-dose steroids; inadequate dosing leads to persistent hyperglycemia 2, 1
• Be aware that insulin requirements will change if the prednisone dose is tapered; plan to reduce NPH by 10-20% with steroid dose reductions 1
• Consider prescription of glucagon for emergent hypoglycemia, particularly important during insulin dose adjustments 2, 3