What is the recommended starting dose of prednisone (corticosteroid) for a patient with a history of diabetes (diabetes mellitus) presenting with severe itching?

Prednisone Dosing for Severe Pruritus in a Patient with Diabetes

For severe pruritus requiring systemic corticosteroids in a patient with diabetes, start prednisone at 0.5 mg/kg/day (approximately 30-40 mg daily for most adults), given as a single morning dose before 9 am. 1

Rationale for This Dose

The most relevant guideline for severe pruritus recommends prednisone 0.5-1 mg/kg/day for grade 3 pruritus (intense or widespread, limiting self-care or sleep). 1 Given your patient's diabetes history, starting at the lower end of this range (0.5 mg/kg/day) balances efficacy with minimizing hyperglycemic risk. 1

Why Not Higher Doses?

• Doses above 0.75 mg/kg/day do not confer additional benefit for inflammatory conditions but significantly increase mortality and complications. 1
• The FDA label specifies that initial dosing may range from 5-60 mg/day depending on disease severity, with lower doses preferred when feasible. 2
• For patients with diabetes as a relative contraindication, lower initial doses (10-20 mg daily) have proven effective in some IgG4-related conditions, though this may be insufficient for severe pruritus. 1

Critical Timing and Administration

Administer the entire daily dose in the morning before 9 am. 2 This timing is crucial because:

• Prednisone causes hyperglycemia predominantly from midday to midnight, not in the morning hours. 3
• Morning administration aligns with natural cortisol rhythms and minimizes adrenal suppression. 2
• Taking with food reduces gastric irritation. 2

Managing Diabetes During Prednisone Therapy

Expected Glycemic Pattern

Your patient will experience postprandial hyperglycemia primarily from midday to midnight, with relative sparing of fasting glucose. 3 This occurs due to:

• Suppression of insulin secretion after breakfast
• Decreased insulin action that peaks in afternoon/evening
• Effects that dissipate overnight 3

Insulin Management Strategy

Use an NPH insulin-based protocol rather than basal-bolus with glargine for prednisone-induced hyperglycemia. 4 Specifically:

• For prednisone >40 mg/day: NPH insulin 0.3 U/kg given between 0600-2000 hours if eating, or 0.2 U/kg between 2000-0600 hours if NPO 4
• For prednisone 10-40 mg/day: NPH insulin 0.15 U/kg given between 0600-2000 hours if eating, or 0.1 U/kg between 2000-0600 hours if NPO 4

If your patient is already on insulin, increase the pre-prednisone insulin dose by at least 30% and be prepared to make larger dose adjustments than usual. 5

Why NPH Over Glargine?

NPH insulin better matches the midday-to-midnight hyperglycemic pattern caused by prednisone, whereas glargine-based regimens may undertreat daytime hyperglycemia and cause nocturnal hypoglycemia. 5, 4

Treatment Duration and Tapering

Continue high-dose prednisone until pruritus is controlled (typically 2 weeks), then taper over 2 weeks. 1 For severe cases:

• Maintain initial dose until symptoms resolve
• Taper gradually in small decrements
• Monitor for symptom recurrence during taper 1

Never abruptly discontinue after more than 3 weeks of therapy due to adrenal suppression risk. 2 When tapering below 10 mg daily, reduce by 1 mg every 4 weeks to minimize adrenal insufficiency. 6

Monitoring Requirements

Glycemic Monitoring

• Check pre-meal and bedtime glucose levels daily for the first 5 days 4
• Expect glucose elevations primarily at lunch, dinner, and bedtime—not fasting 3
• Target glucose range: 4-10 mmol/L (72-180 mg/dL) 5

Clinical Monitoring

• Assess pruritus severity at 2-4 weeks to determine treatment response 1
• Monitor blood pressure, as prednisone can worsen hypertension 2
• Watch for skin changes (bruising, thinning), though these are more common with chronic use 7

Common Pitfalls to Avoid

1. Don't give prednisone in the evening—this maximizes hyperglycemia and disrupts sleep 2, 3
2. Don't use sliding scale insulin alone—it's reactive rather than proactive and won't adequately control prednisone-induced hyperglycemia 4
3. Don't assume fasting glucose reflects overall control—prednisone primarily affects postprandial glucose 3
4. Don't continue high doses beyond 4 weeks without reassessment—prolonged high-dose therapy increases complications without additional benefit 1

Alternative Considerations

If diabetes control becomes unmanageable or the patient has other contraindications (severe osteoporosis, psychiatric conditions), consider:

• Topical high-potency corticosteroids (clobetasol propionate 0.05%) for localized areas 1
• GABA agonists (gabapentin 100-300 mg TID or pregabalin) as adjunctive therapy 1
• Oral antihistamines (cetirizine 10 mg daily, hydroxyzine 10-25 mg QID) 1

However, for "itching like crazy" as you describe, systemic corticosteroids remain the most effective option, and the diabetes can be managed with appropriate insulin adjustments. 1, 4