What is the recommended NPH (Novolin N (NPH) insulin) dose, carbohydrate ratio, and correction scale for a patient transitioning from methylprednisolone (Medrol) 1000mg to prednisone (Deltasone) 100mg?

NPH Insulin Dosing During Steroid Taper

Reduce the NPH dose to approximately 29 units (20% reduction from current 36 units), maintain the carbohydrate ratio at 1:5, and adjust the correction scale to 1 unit per 20 mg/dL above target (instead of 1:15). 1

Rationale for NPH Dose Reduction

The transition from methylprednisolone 1000 mg to prednisone 100 mg represents a significant reduction in glucocorticoid potency. Methylprednisolone 1000 mg is approximately equivalent to prednisone 1250 mg in anti-inflammatory effect, so dropping to prednisone 100 mg is roughly a 90% reduction in steroid exposure. 1

• The American Diabetes Association recommends reducing NPH insulin by 10-20% when tapering steroids to prevent hypoglycemia. 1
• For this magnitude of steroid reduction (from methylprednisolone 1000 mg to prednisone 100 mg), a 20% reduction in NPH is appropriate, yielding approximately 29 units. 1
• Continue morning administration of NPH to match the pharmacokinetic profile of the once-daily prednisone dose. 1, 2

Carbohydrate Ratio Adjustment

Maintain the current 1:5 carbohydrate ratio initially, then reassess after 24-48 hours. 1

• While guidelines suggest reducing prandial insulin by 25-30% during steroid tapers, the patient is still on a substantial prednisone dose (100 mg). 1
• The 1:5 ratio is already relatively aggressive and appropriate for high-dose steroid coverage. 2
• If hypoglycemia occurs postprandially, liberalize the ratio to 1:6 or 1:7. 1

Correction Scale (Insulin Sensitivity Factor)

Change the correction scale from 1 unit per 15 mg/dL to 1 unit per 20 mg/dL above target. 2

• The "1800 rule" provides a starting correction factor: 1800 ÷ total daily insulin dose. 2
• With reduced NPH (29 units) plus estimated prandial insulin (~15-20 units daily), total daily dose is approximately 45-50 units. 2
• This yields a correction factor of approximately 1 unit per 36-40 mg/dL, but given ongoing high-dose steroid use, a more aggressive 1:20 ratio is appropriate. 2

Specific correction scale:

• Blood glucose 150-200 mg/dL: 2-3 units 2
• Blood glucose 201-250 mg/dL: 4-5 units 2
• Blood glucose 251-300 mg/dL: 6-7 units 2
• Blood glucose 301-350 mg/dL: 8-10 units 2
• Blood glucose >350 mg/dL: 10-12 units and notify provider 2

Monitoring Strategy

• Check blood glucose every 4-6 hours, particularly before meals and at bedtime. 2
• Target blood glucose range of 100-180 mg/dL is appropriate for steroid-induced hyperglycemia. 2
• If hypoglycemia (glucose <70 mg/dL) occurs, reduce NPH by an additional 10-20% (to approximately 23-26 units). 1, 2
• If persistent hyperglycemia continues despite these adjustments, increase NPH by 2 units every 3 days until target is achieved. 1

Critical Pitfalls to Avoid

• Do not reduce insulin doses too aggressively despite the steroid taper—prednisone 100 mg is still a high dose that causes significant hyperglycemia. 3, 4
• Research shows that even with steroid dose reductions, insulin requirements often need to be increased over the first 3 days due to cumulative steroid effects. 3
• Failing to match NPH timing with morning prednisone administration leads to inadequate daytime coverage and nocturnal hypoglycemia. 2, 3
• If the patient develops nocturnal hypoglycemia with adequate daytime control, consider splitting the NPH dose (2/3 morning, 1/3 evening). 1

Special Considerations for This Patient

• The initial NPH dose of 36 units (approximately 0.5 units/kg for a typical 70 kg patient) was appropriate for methylprednisolone 1000 mg. 3
• Research demonstrates that patients on prednisolone ≥20 mg require initial insulin doses of 0.5 units/kg or 130% of baseline insulin. 3
• The 29-unit NPH dose represents approximately 0.4 units/kg, which aligns with recommendations for high-dose glucocorticoid coverage. 2