Skin disorders in patients with diabetes mellitus: a review

Diabetes mellitus (DM) is a frequent metabolic disease whose prevalence is estimated to be around 9.3 % in the world population in the age group 20—79, corresponding to 463 million affected subjects. Moreover, this prevalence will probably increase in the course of the next years. It accounts for more than 90% of the diabetic patients. Besides systemic complications, those ay also be observed in dermatology. According to the region, the prevalence of skin disorders in patients suffering DM is ranging from 35.4 to 98.8 %. This makes these symptoms a frequent cause of consultation in dermatological practice. The most occurring disorders are skin infections, but yellow nails, candidiasis, acrochordons, limited joint mobility and idiopathic guttate hypomelanosis may also be frequently observed. Diabetic dermopathy and diabetic foot syndrome are also common, such as pigmentation disorders such as acanthosis nigricans and vitiligo. Differences between patterns of lesions remain unclear among types of DM (type 1 or type 2). Overall, cutaneous infection and xerosis showed to be highly prevalent and important skin disorders in several studies, regardless DM type. Among cutaneous infections, fungal aetiology appears to be the most common and those with bacterial origin are the less frequent.DM affects the skin through several mechanisms — High levels of glycaemia strongly affect skin homeostasis by impairing the normal functioning of keratinocytes in vitro, decreasing their proliferation and differentiation. They also lead to advanced glycation end products (AGEs) formation. The latter are formed from glycation of proteins, lipids and nucleic acids. They have various deleterious effects at skin levels: inducing reactive oxygen species (ROS) formation, impairing ROS clearance, as well as intra and extracellular proteins function, and inducing pro inflammatory cytokine through nuclear factor κβ (NF-κβ) pathway. AGE alters collagen properties, decreasing flexibility and solubility and increasing its rigidity, thickening dermal collagen, with increased cross linking from non-enzymatic glycosylation, participating in the development of fibrosis. In diabetic patients, the vascular changes found in the skin are similar to those caused by UV-exposure, i. e. thickening of the vessels walls, increasing from thigh to foot and most marked in the capillaries and leading to failure of vascular responsivenessThis paper is aimed to summarize all these pathologies, reporting their prevalence, giving a brief description of the symptoms, of their pathogenesis and guidelines for their management. Dermatologists have a key role in their treatment, but also in detecting new cases of DM when taking in charge these pathologies. They must also promote glycaemic control by these patients.