Diabetes: Cutaneous Manifestations

  • Acanthosis nigricans is an asymptomatic darkening and thickening of certain areas of the skin associated with insulin resistance. Patients develop tan or brown velvety plaques, most commonly on the intertriginous areas of the axilla, groin and posterior neck. Lesions show marked hyperkeratosis and papillomatosis with mild acanthosis and hyperpigmentation. In 2000, the American Diabetes Association established acanthosis nigricans as a formal risk factor for diabetes in children.

  • Necrobiosis lipoidica dibeticorum (NLD) is a collagen degeneration disease that results in a granulomatous response, thickening of blood vessel walls & fat deposition. Lesions present as asymptomatic, shiny, red-brown patches that increase in size over months to years, becoming more yellow & atrophic. Most lesions have a fairly well defined border, occur on the lower extremities & can ulcerate if subjected to trauma. Only about 25% of patients experience pain, because many have nerve damage.

  • Bullous diabeticorum is a distinct, spontaneous, noninflammatory blistering condition of acral skin that resembles burn blisters and occurs in 0.5% of patients with diabetes – usually among those with severe forms of the disease and neuropathy. These blisters typically occur on the fingers, hands, toes, feet, legs or forearms, and are painless and self-limiting.

  • Eruptive xanthomatosis occurs when triglyceride levels in the blood rise to extremely high levels due to severe insulin resistance. Eruptive xanthomas appear as firm, yellow, waxy pea-like bumps on the skin that are surrounded by itchy, red halos. These lesions typically occur on the face and buttocks, as well as the backs of arms, legs and hands. Eruptions generally resolve when glycemic control is restored, but lipid-lowering drugs may also be needed.

  • Granuloma annulare is a benign self-limited dermatosis that has been epidemiologically linked to diabetes and necrobiosis lipoidica diabeticorum. Lesions appear as sharply defined, ring or arc-shaped firm, nontender soft tissue nodules on the extremities, scalp or forehead. Papules are 1-5 mm in diameter, flesh-colored or slightly pink and smooth rather than scaly. Treatment usually is not required, but topical steroids such as hydrocortisone, may help.

  • Vitiligo, an autoimmune disorder in which the destruction of melanocytes results in skin depigmentation, occurs at a higher incidence among adults with type 1 diabetes. The association between the two disorders remains unclear, but researchers have suggested that type 1 diabetes and vitiligo may share a common autoimmune etiology. It is recommended that clinicians evaluate patients who experience late-onset vitiligo for diabetes.

  • Diabetic foot ulcers are separated into two categories: ischemic and neuropathic ulcers. The ischemic patient will present with disproportionately excruciating pain associated with a superficial ulcer, while the neuropathic patient is unaware of a large, deep ulcer. As many as four-fifths of patients with diabetes experience peripheral neuropathy, and the majority of ulceration occurs as a consequence of the loss of protective sensations such as temperature and pain.

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Nearly one-third of patients with diabetes have some type of dermatologic manifestation and, with time, the skin of all patients with diabetes will be affected in some form or another.

Cutaneous manifestations of diabetes can be extremely valuable to the clinician. Some, such as diabetic bullae and necrobiosis lipoidica diabeticorum, can alert clinicians to the diagnosis of diabetes; whereas others, such as eruptive xanthomas can reflect the status of a patient’s glucose and lipid metabolism.