What insulin adjustments should I make for a patient on prednisone 60 mg daily and NPH insulin 20 units administered at 8 am who has capillary glucose of 201 mg/dL at noon and 325 mg/dL at 5 pm?

Insulin Adjustment for Steroid-Induced Hyperglycemia

Increase your morning NPH insulin to 28–32 units at 8 AM and add 6–8 units of rapid-acting insulin before lunch and 8–10 units before dinner to address the afternoon and evening hyperglycemia caused by prednisone 60 mg. 1

Understanding the Steroid-Induced Hyperglycemia Pattern

• Prednisone 60 mg taken in the morning causes peak hyperglycemia 4–12 hours after administration, predominantly affecting glucose levels from midday through midnight 1, 2, 3
• Your current NPH 20 units at 8 AM is insufficient to cover the massive insulin resistance induced by high-dose prednisone, resulting in the 201 mg/dL at noon and 325 mg/dL at 5 PM readings 1, 4
• Morning fasting glucose typically remains normal or only mildly elevated with once-daily morning prednisone, but afternoon/evening glucose rises dramatically 1, 2

Immediate NPH Insulin Adjustment

• Increase morning NPH from 20 units to 28–32 units (40–60% increase) to provide adequate basal coverage during the steroid's peak effect 1, 4
• NPH insulin should be administered concomitantly with the morning prednisone dose because NPH peaks at 4–6 hours, matching the steroid's hyperglycemic effect 1
• For high-dose glucocorticoids (prednisone ≥40 mg/day), an initial NPH dose of 0.3 units/kg is recommended if eating, which would be approximately 20–25 units for an average adult, but your current hyperglycemia indicates you need the higher end of this range 4

Add Prandial Insulin Coverage

• Start 6–8 units of rapid-acting insulin (lispro, aspart, or glulisine) before lunch to address the 201 mg/dL reading 1
• Start 8–10 units of rapid-acting insulin before dinner to address the 325 mg/dL reading 1
• Administer rapid-acting insulin 0–15 minutes before meals for optimal postprandial control 1
• Prandial insulin requirements often increase by 40–60% or more when on high-dose steroids compared to baseline needs 1

Correction Insulin Protocol

• Add 2 units of rapid-acting insulin for pre-meal glucose >250 mg/dL 1, 5
• Add 4 units of rapid-acting insulin for pre-meal glucose >350 mg/dL 1, 5
• These correction doses are in addition to your scheduled prandial insulin 1, 5

Titration Schedule

• Increase morning NPH by 4 units every 3 days if pre-lunch glucose remains >180 mg/dL 1
• Increase lunch rapid-acting insulin by 2 units every 3 days if 2-hour post-lunch glucose is >180 mg/dL 1
• Increase dinner rapid-acting insulin by 2 units every 3 days if 2-hour post-dinner glucose is >180 mg/dL 1
• Target fasting glucose 80–130 mg/dL and postprandial glucose <180 mg/dL 1

Monitoring Requirements

• Check glucose before each meal and at bedtime (minimum 4 times daily) 1
• Check 2-hour post-lunch and post-dinner glucose to guide prandial insulin titration 1, 5
• Check fasting glucose daily to assess NPH adequacy 1

Critical Threshold for NPH Dosing

• Do not increase NPH beyond 0.5 units/kg/day (approximately 35–40 units for most adults) without ensuring adequate prandial coverage, as this leads to "overbasalization" with increased hypoglycemia risk 1
• When NPH approaches this threshold and glucose remains elevated, focus on increasing prandial insulin rather than further NPH escalation 1

Alternative NPH Dosing Strategy

• If once-daily morning NPH proves insufficient even at higher doses, consider splitting NPH to twice daily: approximately 18–20 units at 8 AM and 10–12 units at bedtime 1
• This split dosing provides better afternoon/evening basal support while reducing nocturnal hypoglycemia risk 1, 6

Evidence from Clinical Trials

• A randomized trial in hospitalized patients on prednisone ≥10 mg/day showed that an NPH-based protocol achieved mean glucose of 226 mg/dL versus 269 mg/dL with usual care (p<0.0001) 4
• The same trial demonstrated significant improvements in fasting glucose (171 vs 221 mg/dL) and pre-lunch glucose (208 vs 266 mg/dL) with NPH-based therapy 4
• Continuous glucose monitoring studies confirm that prednisone causes hyperglycemia predominantly from 1200–2400 hours, with mean glucose 142 mg/dL during this period versus 112 mg/dL from midnight to noon 2

Hypoglycemia Management

• Treat any glucose <70 mg/dL immediately with 15 grams of fast-acting carbohydrate 1
• If hypoglycemia occurs without clear cause, reduce the implicated insulin dose by 10–20% immediately 1
• Never give rapid-acting insulin at bedtime as a sole correction dose, as this markedly increases nocturnal hypoglycemia risk 1

Common Pitfalls to Avoid

• Do not rely solely on correction insulin to manage steroid-induced hyperglycemia; scheduled prandial doses are essential 1, 5
• Do not delay adding prandial insulin when pre-meal glucose repeatedly exceeds 180 mg/dL on high-dose steroids 1, 5
• Do not use sliding-scale insulin as monotherapy; this approach is condemned by major diabetes guidelines and leads to dangerous glucose fluctuations 1
• Do not continue increasing NPH beyond 0.5 units/kg/day without addressing postprandial hyperglycemia with prandial insulin 1

Expected Clinical Outcomes

• With properly adjusted NPH and prandial insulin, approximately 68% of patients achieve mean glucose <140 mg/dL, compared with only 38% using inadequate regimens 1
• Total daily insulin requirements on prednisone 60 mg may be 40–60% higher than baseline, often reaching 50–70 units total daily dose 1, 3

When Prednisone is Tapered

• Reduce NPH by 10–20% for each 10 mg reduction in prednisone dose to prevent hypoglycemia 5
• Reduce prandial insulin by 20–30% as steroid dose decreases 5
• Monitor glucose closely during taper, as insulin needs may drop rapidly within 24–48 hours of steroid reduction 5