The Nail in Diabetes Mellitus

Diabetes mellitus may affect all organ systems of the human body; however, nail changes are almost all indirect and related either to the specific biochemical action of high glucose levels, the inherent immunosuppression with increased susceptibility to mainly bacterial and fungal infections, the vascular impairment associated with diabetes, and particularly the diabetic neuropathy. All these factors act together and can damage the nail unit in many different ways. Yellow, brittle, often opaque nails are frequent and splinter hemorrhages may be observed. Bacterial infections are commonly seen as acute paronychia, whereas Candida strains usually cause chronic infections. Pseudomonas aeruginosa may form bacterial biofilms on the nails’ undersurface and stain it green. Onychomycoses, mostly co-occurring with dermatophyte foot infections, are very frequent, and their prevalence is related to the blood sugar level. Diabetic vasculopathy may cause variable nail alterations. Together with diabetic neuropathy, they lead to diabetic foot syndrome with a profound impact on the nail unit. Finally, the nail unit may also serve as a diagnostic tool giving information on the long time course of diabetes.