What should the NPH (Neutral Protamine Hagedorn) insulin dose and carb ratio be for a 71kg patient with type 2 diabetes, BMI (Body Mass Index) 26, currently on 30 units of Tresiba (insulin degludec) per day, who will receive 500mg of intravenous methylprednisolone?

NPH Insulin Dosing and Carbohydrate Ratio for Steroid-Induced Hyperglycemia

For a 71kg patient with type 2 diabetes on Tresiba 30 units daily receiving methylprednisolone 500mg IV, start NPH insulin at 21-28 units in the morning (0.3-0.4 units/kg) and use a carbohydrate ratio of 1:8-10 grams. 1

NPH Insulin Dose Calculation

Initial NPH dosing should be 0.3-0.4 units/kg for patients on high-dose glucocorticoids, which for this 71kg patient equals approximately 21-28 units. 1 This dose should be administered in the morning to coincide with the peak hyperglycemic effect of methylprednisolone, which occurs 4-8 hours after administration. 1, 2

Basal Insulin Management

• Continue the current Tresiba 30 units daily while adding NPH to specifically address the steroid effect. 1 The Tresiba provides baseline basal coverage, while the NPH targets the steroid-induced hyperglycemia pattern.
• The combined approach prevents both fasting hyperglycemia (covered by Tresiba) and the characteristic midday-to-midnight hyperglycemia from steroids (covered by NPH). 1, 2

Dosing Rationale

• High-dose glucocorticoids like methylprednisolone 500mg IV require aggressive insulin coverage, potentially 40-60% more than standard dosing. 2, 3
• The 0.3-0.4 units/kg recommendation is specifically for patients receiving high-dose steroids, not standard basal insulin initiation. 1
• Morning administration is critical—NPH peaks at 4-6 hours, matching the steroid's hyperglycemic effect. 2

Carbohydrate Ratio

Start with a carbohydrate ratio of 1:8-10 (1 unit of rapid-acting insulin for every 8-10 grams of carbohydrate). 1 This is more aggressive than standard ratios due to steroid-induced insulin resistance.

Meal-Specific Adjustments

• For meals with the greatest postprandial glucose excursions, consider a more aggressive ratio of 1:6. 1
• The lunch and dinner meals typically require the most aggressive coverage due to the timing of steroid effects. 1, 2
• Standard carbohydrate ratios (1:10-15) used in the general diabetes population are insufficient for steroid-induced hyperglycemia. 4

Correction Scale

Use the 1800 rule as a starting point: correction factor = 1800 ÷ total daily insulin dose. 1 For this patient with approximately 50-60 units total daily dose (30 units Tresiba + 25 units NPH + prandial insulin), the correction factor would be approximately 1 unit per 30-36 mg/dL above target.

Recommended Correction Scale

• Blood glucose 150-200 mg/dL: 2 units 1
• Blood glucose 201-250 mg/dL: 4 units 1
• Blood glucose 251-300 mg/dL: 6 units 1
• Blood glucose 301-350 mg/dL: 8 units 1
• Blood glucose >350 mg/dL: 10 units and notify provider 1

Monitoring Requirements

Monitor blood glucose every 4-6 hours while adjusting therapy. 4, 1 Target blood glucose should be 100-180 mg/dL for this patient. 1

Adjustment Protocol

• If hypoglycemia occurs, reduce the corresponding insulin dose by 10-20%. 1, 2
• For persistent hyperglycemia, increase NPH by 2 units every 3 days until target blood glucose is achieved. 2, 3
• Daily fasting blood glucose monitoring is essential during the titration phase. 3

Critical Pitfalls to Avoid

Failing to match the timing of NPH insulin with steroid administration leads to inadequate coverage of steroid-induced hyperglycemia. 1 The NPH must be given in the morning when methylprednisolone is administered to align the insulin peak with the steroid's hyperglycemic effect.

Steroid Taper Considerations

• As the steroid dose is tapered, reduce the NPH insulin dose proportionally, typically 10-20% reduction for each significant decrease in steroid dose. 1, 2
• Failing to reduce insulin doses as steroids are tapered results in hypoglycemia. 1
• The Tresiba dose should remain stable unless fasting glucose patterns change. 1

Common Errors

• Using only correction insulin without scheduled basal-bolus coverage leads to suboptimal control. 4, 3
• Continuing to escalate basal insulin beyond 0.5 units/kg/day without addressing postprandial hyperglycemia causes overbasalization. 3
• Not recognizing that methylprednisolone 500mg IV is equivalent to approximately 625mg of prednisone, requiring substantial insulin coverage. 5

Special Considerations

• Patients with kidney transplants often have increased insulin resistance due to immunosuppressive medications and steroids. 1 This patient may require doses at the higher end of the recommended range.
• The BMI of 26 indicates mild overweight, which may contribute to baseline insulin resistance. 1
• Research shows that methylprednisolone pulses produce significant fasting hyperglycemia in 94-98% of patients by the third day. 6