Nerve ultrasonographic findings in diabetes mellitus are determined by anatomical location and type of diabetes

•Diffuse mild-to-moderate increase in nerve size was found in diabetes, most pronounced at compression sites on the upper limbs.•Type 2 diabetes has a more robust effect on nerve size than type 1 diabetes.•Nerve enlargement occurs even before the detection of diabetic polyneuropathy, with increase in the early stages of polyneuropathy.