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Diabetes Complications: More Than Skin Deep

About 16 million Americans have diabetes, an illness in which the pancreas produces insufficient insulin (the hormone responsible for the uptake of glucose by body tissues). About 90% have type 2 diabetes, which develops gradually after about age 40. The remainder have type 1 diabetes, which usually occurs much earlier. At some point during the course of their illness, at least one third of sufferers are bothered by troublesome skin disorders.

Proper skin care and long-term control of blood glucose levels may reduce the risk of some of these skin problems. Without treatment, complications can arise, including open sores (ulcers) and, in very severe cases, even gangrene or life-threatening infection. Skin problems in a person with diabetes may indicate the need for more aggressive diabetes management; in otherwise healthy people, some skin abnormalities may signal a need for an evaluation to determine if diabetes is present.

Risk of Infection

Anyone can develop a skin infection, but people with diabetes are especially vulnerable. In one study of 457 patients, 20% of those with type 2 diabetes had a skin infection. Such infections are generally either bacterial or fungal.

Bacterial infections are usually caused by one or more of several staphylococcus, streptococcus, or pseudomonas organisms. The infected area is typically hot, red, and itchy. Common manifestations include styes (infections of the glands of the eyelid), boils (infections of the hair follicles), carbuncles (deep infections of the skin and the tissue underneath), and infections around the nails.

A yeast known as Candida albicans is responsible for most fungal infections. It usually causes an itchy, red, moist rash surrounded by tiny pimples, usually in the warm, moist folds of the skin. Candida albicans is also a frequent cause of a vaginal infection characterized by a white, cheesy discharge and marked itching. Fungi known as dermatophytes cause other rashes, including "jock itch" and "athlete's foot."

Skin infections should be treated by a physician. Without proper care, they may not heal or can spread throughout the body. Good skin-care habits can also speed recovery and may reduce the likelihood that an infection will occur in the first place (see "Keeping Skin Healthy").

Other Skin Problems

Most noninfective diabetic skin disorders appear in people who have had diabetes for many years. But skin changes may also be the first manifestation of diabetes and often prompt doctors to screen for diabetes. The two most common, diabetic dermopathy (DD) and various types of skin thickening, are relatively benign. Although both may cause permanent skin changes, they are not painful.

Also called shin spots, DD is the most common skin disorder seen in older people with diabetes. It is characterized by round or oval reddish-brown spots on both shins. Spots sometimes also appear on the forearms, the sides of the feet, and the front of the lower thighs. Although the affected area may become permanently discolored, there is no discomfort. DD spots can develop in nondiabetics, but this is relatively rare.

The most common place for skin to thicken is on the backs of the hands and fingers, especially over the knuckles. Although there are no treatments for either condition, skin thickening may subside over time.

A condition called acanthosis nigricans (AN) typically strikes people with diabetes who are very obese. AN is characterized by raised, velvety tan or brown spots on the sides of the neck, armpits, and groin, and sometimes on the top of the hands, elbows, and knees. Perspiration typically causes the lesions to itch. Weight loss may prevent the development of new spots, and prescription creams can help minimize discoloration.

Other skin disorders can be more troublesome. A condition called necrobiosis lipoidica (NL) causes red, well-defined, bite-like bumps or flat lesions (papules) on the legs. As they develop, the lesions expand and flatten into saucer-like plaques, and nearly one third ulcerate. About 80% of NL cases occur in women. Although there is no cure, treatment with oral, injectable, or topical medications can help limit ulceration, relieve discomfort, and speed healing. Only 0.3% of diabetics have NL, but most people with NL also have diabetes, elevated blood glucose levels, or a family history of diabetes. Therefore, anyone with NL who has not been diagnosed with diabetes should be screened for it. People with NL and a negative screening test should be reevaluated yearly.

People with long-standing diabetes and diabetic neuropathy (damage to nerves supplying the feet and hands) may develop a disorder called bullosis diabeticorum (BD). It is characterized by clear, fluid-filled blisters (bullae) that spontaneously arise from apparently normal skin. The blisters usually appear on the feet and toes but can also develop on the hands and fingers. Although the blisters generally heal on their own, skin-care measures (such as keeping affected areas clean and protected) can help prevent secondary infection.

Keeping Skin Healthy

For most people, a little skin pampering is a pleasure. For people with diabetes, it is an essential component of health care. The following measures are wise for everyone, but they are indispensable for those with diabetes:

Control blood glucose levels. Elevated blood glucose may increase susceptibility to infection.

Moisturize. Use an oil-in-water skin moisturizer (such as Eucerin Original Lotion) or a lighter water-in-oil product (such as Lubriderm or Alpha-Keri). Except when using an antifungal cream, do not put creams between the toes, where extra moisture may encourage fungal infection.

Bathe properly. Use warm water (which is less drying than hot water) and mild, moisturizing bath products (such as Dove soap).

Dry off gently and thoroughly. Pat the skin dry, paying special attention to folds in the skin and the areas between the toes, but leave other skin surfaces slightly damp and seal that moisture into the skin with moisturizing cream.

Humidify. Increase indoor humidity with a humidifier, especially during the winter, when the air tends to be driest.

Care for your feet. Visually inspect the feet for irritation and sores every evening when you remove your shoes.

Treat cuts and scrapes promptly. Flush the injured area with water and wash it with antibacterial soap (Mercurochrome, antiseptic, alcohol, and iodine are too harsh). Check with your doctor before using over-the-counter topical antibiotics.

Know when to see a doctor. Major cuts, burns, infections, and skin problems that persist require professional care.


From The Johns Hopkins Medical Letter: Health After 50, January 2000.


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The Diabetes White Paper from The Johns Hopkins White Papers series is an annual, in-depth report written by Hopkins physicians.

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