There is increasing evidence that coronavirus disease 2019 (COVID-19) may lead to new-onset diabetes mellitus (DM). This may occur even in patients without predisposing factors for impaired glucose metabolism. Both impaired pancreatic insulin secretion and insulin resistance have been implicated as underlying mechanisms. Importantly, new-onset hyperglycaemia is associated with worse prognosis in patients with COVID-19. Indeed, its prognosis may be even more sinister than in patients with pre-existing DM. More research data and knowledge are currently being collected to improve our insights into this constellation and to guide therapies in clinical reality.

: The aim of the present brief review was to discuss carpal tunnel syndrome (CTS) in diabetes mellitus (DM). Generally, CTS is more common in DM, especially in subjects with coexisting diabetic polyneuropathy (DPN) and/or long DM duration. There is no agreement if it is more frequent in type 1 or type 2 DM. The precise underlying mechanisms are not entirely clear but appear to involve hyperglycaemia-induced median nerve oedema, increased sensitivity to exogenous trauma and nerve myelin ischaemia and axonal degeneration. More recently, increased vascular endothelial growth factor (VEGF) and advanced glycation endproducts (AGEs) appear to also play an important role. Median nerve conduction study remains the cornerstone of CTS diagnosis in DM, being more sensitive than clinical examination. Treatment of CTS is medical or surgical. The latter appears now to be equally effective in subjects with vs. without DM in terms of recurrence rates and quality of life.

The aim of the present brief review was to discuss Bell’s palsy (BP) in diabetes mellitus (DM). The risk of BP is increased in DM. DM subjects with BP are more prone to severe facial nerve degeneration. Further characteristics of BP in DM include: a) infrequent taste impairment; b) more frequent and more marked facial nerve subclinical electrophysiological impairment; c) more frequent BR impairment; d) potentially concurrent distal symmetrical sensorimotor polyneuropathy; e) more frequent alternating BP with recurrent episodes affecting different sides of the face.