This article describes a male Labrador with diabetes mellitus that had been treated with corticosteroids for several years because of atopy. The six-year-old dog was presented at the department of Small Animal Medicine and Clinical Biology with extreme muscular weakness. Electrofysiological examination revealed a peripheral polyneuropathy. It seemed very likely that the neuropathy was a consequence of the diabetes. A successful treatment of this diabetes neuropathy, a rare complication of diabetes mellitus in the dog, is described.