Cutaneous manifestations of diabetes mellitus.

Diabetes mellitus is a common condition, and persons who have this ailment are commonly encountered by dermatologists and primary care physicians. Because glucose attaches to long-lived proteins, it may have a profound effect on the tertiary structure of the protein. Chronic hyperglycemia may be responsible for the pathogenesis of many diabetic complications. It has been suggested that increased cross-linking of collagen in diabetic patients is responsible for the fact that their skin is generally thicker than that of nondiabetics. Advanced glycosylation end-products are probably responsible for yellowing of skin and nails. Increased viscosity of blood caused by stiff red blood cell membranes results in engorgement of the postcapillary venules in the papillary dermis, which is detected as erythema of the face or as periungual erythema. It is suggested that these skin changes may eventually be used as a reflection of the patient's current (as well as past) metabolic status.