Diabetes mellitus and skin diseases

Dermatologic manifestations of diabetes mellitus: a review

Diabetes mellitus affects every organ of the body including the skin. Certain skin manifestations of diabetes are considered cutaneous markers of the disease, whereas others are nonspecific conditions that occur more frequently among individuals with diabetes compared with the general population. Diabetic patients have an increased susceptibility to some bacterial and fungal skin infections, which account, in part, for poor healing. Skin complications of diabetes provide clues to current and past metabolic status. Recognition of cutaneous markers may slow disease progression and ultimately improve the overall prognosis by enabling earlier diagnosis and treatment.

Skin blood flow in necrobiosis lipoidica diabeticorum

BACKGROUND

Necrobiosis lipoidica diabeticorum (NLD) is a granulomatous skin reaction found in < 1% of diabetic patients. Our purpose was to determine if NLD represented areas of cutaneous ischemia.

METHODS

Using laser Doppler flowmetry, we measured cutaneous blood flow in nine diabetic patients at NLD lesions and at contiguous uninvolved sites. Flow values were also determined at several reference sites noncontiguous with the NLD lesions and compared to age- and sex-matched controls: 24 diabetic subjects without skin abnormalities, 18 diabetic patients with dermopathy, and 40 nondiabetic subjects.

RESULTS

NLD lesions exhibited significantly higher blood flow (4.8 +/- 0.7 ml/min/100 g) than areas of unaffected skin close to the lesions (1.2 +/- 0.1 ml/min/100 g) (P < 0.01 for both comparisons). There were no significant differences in flow between normal skin sites in NLD patients and normal sites in diabetic patients without skin lesions.

CONCLUSIONS

Our findings refute the hypothesis that NLD is a manifestation of microvascular ischemic disease of the skin. The increased blood flow seen in NLD lesions suggests an ongoing inflammatory process.

Manifestations of cutaneous diabetic microangiopathy

The etiologies of a variety of skin conditions associated with diabetes have not been fully explained. One possible etiological factor is diabetic microangiopathy, which is known to affect the eyes and kidneys in patients with diabetes. There are many mechanisms by which diabetes may cause microangiopathy. These include excess sorbitol formation, increased glycation end products, oxidative damage, and protein kinase C overactivity. All of these processes occur in the skin, and the existence of a cutaneous diabetic microangiopathy has been well demonstrated. These microangiopathic changes are associated with abnormalities of skin perfusion. Because the skin plays a thermoregulatory role, there is significant capillary redundancy in normal skin. In diabetic patients, loss of capillaries is associated with a decrease in perfusion reserve. This lost reserve is demonstrable under stressed conditions, such as thermal stimulation. The associated failure of microvascular perfusion to meet the requirements of skin metabolism may result in diverse skin lesions in patients with diabetes. Many skin conditions peculiar to diabetes are fairly rare. Necrobiosis lipoidica diabeticorum (NLD) and diabetic bullae occur very infrequently as compared with diabetic retinopathy and nephropathy. Conversely, there is a correlation between diabetic microvascular disease and NLD. This correlation also exists with more common skin conditions, such as diabetic dermopathy. This relationship suggests that diabetic microangiopathy may contribute to these conditions even if it is not primarily causal. Clinically, the major significance of diabetic cutaneous microangiopathy is seen in skin ulceration which is very common and has a major impact on diabetic patients. Many factors contribute to the development of diabetic foot ulcers. Neuropathy, decreased large vessel perfusion, increased susceptibility to infection, and altered biomechanics all play a role, but there is no doubt that inadequate small blood vessel perfusion is a major cause of the inability to heal small wounds that eventually results in ulcer formation. The accessibility of skin capillaries makes cutaneous diabetic microangiopathy an attractive model for research on the evolution of microvascular disease in diabetic patients.

Cutaneous manifestations of endocrine-metabolic disease and nutritional deficiency in the elderly

This article explores cutaneous manifestations of endocrine-metabolic disease and nutritional deficiency in the elderly. Topics covered include the following: diabetes mellitus, thyroid disorders, adrenal dysfunction, pituitary disorders, parathyroid disease, nutritional deficiencies, menopause, and HIV.

Cutaneous manifestations of diabetes mellitus

Diabetes is a common disease with many cutaneous manifestations encountered by dermatologists. Diabetes and the skin may be linked by association (e.g., necrobiosis lipoidica); infection; diabetic complication (e.g., neuropathic ulcer); or treatment reaction. Review of recent studies and reports focuses on pathogenesis and treatment of these many diabetic cutaneous changes.

Dermatologic conditions associated with diabetes

The development of skin manifestations of diabetes affects up to two thirds of patients with both types 1 and 2 diabetes mellitus. Cutaneous manifestations of diabetes occur because of the microvascular complications of diabetes, impaired wound healing, and other yet undetermined mechanisms. This article summarizes the most frequent skin findings in patients with diabetes, and proposes treatment of some complications.

Skin and diabetes

Skin manifestations associated with diabetes mellitus are common and, with close scrutiny, can occur in most, if not all, patients. Little information is available on what common pathophysiologic thread is responsible for the skin manifestation and diabetes. Although controlled studies are lacking, a recognition of the skin manifestations, treatment, and prognosis will help patients and their caregivers to understand treatment alternatives more clearly.

Cutaneous manifestations and consequences of smoking

Cigarette smoking is strongly linked to serious internal diseases such as cancer, cardiovascular disease, and lung disease. However, the external manifestations and consequences of smoking are relatively unknown. Although generally less ominous, the cutaneous manifestations of smoking may be associated with significant morbidity. This article reviews the known adverse effects on the skin of smoking.