How do you treat severe pruritus and scratching in a patient with diabetes mellitus?

Treatment of Severe Pruritus in Diabetes Mellitus

For severe itching in a diabetic patient, start with aggressive emollient therapy and topical corticosteroids, then escalate to gabapentin or pregabalin as second-line systemic therapy if topical measures fail after 2 weeks.

Understanding the Problem

Pruritus affects 18-27% of diabetic patients and stems from two primary mechanisms: skin xerosis (dry skin) and diabetic polyneuropathy (small fiber neuropathy) 1. The presence of severe itching warrants screening for diabetic complications, as it may signal underlying neuropathy, nephropathy, or retinopathy 2.

First-Line Treatment Approach

Aggressive Skin Barrier Management

• Apply high lipid-content emollients multiple times daily to address the defective skin barrier that predisposes diabetic skin to water loss, dryness, and inflammation 3, 1
• Use gentle cleansers specifically designed for diabetic skin care containing urea and essential ceramides 3
• This cornerstone therapy must be optimized before escalating to systemic treatments 4

Topical Anti-Pruritic Therapy

• Start with moderate-to-high potency topical corticosteroids such as mometasone furoate 0.1% ointment or betamethasone valerate 0.1% ointment for at least 2 weeks to exclude asteatotic eczema 5, 4
• Add topical capsaicin 0.025% cream applied 3-4 times daily for significant relief, particularly effective in diabetic neuropathic pruritus 4, 6
• Consider topical agents containing menthol 0.5% or lotions with urea/polidocanol for additional soothing effects 5

Second-Line Systemic Treatment

When to Escalate

Reassess after 2 weeks of optimal topical therapy; if severe pruritus persists or limits activities of daily living or sleep, proceed to systemic treatment 5, 4.

Gabapentinoids (Preferred Systemic Therapy)

• Gabapentin 900-3600 mg daily is the recommended systemic therapy for diabetic neuropathic pruritus that doesn't respond to topical treatments 5, 4
• Pregabalin 25-150 mg daily is an alternative that works by reducing calcitonin gene-related peptide release peripherally and modulating μ-opioid receptors centrally 5, 7
• These agents specifically target the neuropathic component of diabetic itch 5

Antihistamines (Limited Role)

• Non-sedating second-generation antihistamines (loratadine 10 mg daily) may be tried for daytime pruritus, though evidence for efficacy in diabetic pruritus is limited 5, 4
• First-generation sedating antihistamines (diphenhydramine 25-50 mg or hydroxyzine 25-50 mg) can be considered for nighttime pruritus but must be avoided in elderly patients due to increased dementia risk 5, 8

Critical Diagnostic Considerations

Rule Out Systemic Complications

Before attributing pruritus solely to diabetes, obtain:

• Complete blood count to exclude polycythemia vera (aquagenic pruritus) or hematologic malignancy 9, 8
• Liver function tests and bile acids to exclude cholestatic pruritus 9
• Renal function (urea and electrolytes) as 42% of dialysis patients develop uremic pruritus 9, 8
• Ferritin level to assess for iron deficiency or overload 9

When to Biopsy

Perform skin biopsy if:

• Lesions persist after 2 weeks of adequate topical treatment 9
• Small fiber neuropathy needs confirmation (though may be too small to detect on standard testing) 5
• Cutaneous lymphoma or autoimmune bullous disease is suspected 9

Important Pitfalls to Avoid

Glycemic Control

• Beware that high-dose topical corticosteroids can worsen glycemic control in diabetic patients 7
• Once systemic therapy (pregabalin/gabapentin) controls pruritus, reduce topical steroid intensity to improve glucose management 7

Infection Risk

• Repeated scratching creates cutaneous injuries that can lead to hematogenous bacterial dissemination and serious complications like abscess formation 7
• Aggressive pruritus control is essential to prevent these infectious complications 7

Ineffective Treatments to Avoid

• Cetirizine is specifically not effective in diabetic/uremic pruritus and should be avoided 4
• Crotamiton cream has been shown ineffective for generalized pruritus 4

Treatment Algorithm Summary

1. Weeks 1-2: Intensive emollients + moderate-to-high potency topical corticosteroids + topical capsaicin 0.025% four times daily 5, 4, 6

2. If no improvement after 2 weeks: Add gabapentin 900-3600 mg daily OR pregabalin 25-150 mg daily 5, 4

3. If still refractory: Consider broadband UVB phototherapy (if available) or referral to dermatology 4

4. Throughout treatment: Maintain aggressive emollient use, optimize diabetes control, and monitor for complications 3, 1