The morphological findings in peripheral nerves in diabetic subjects are reviewed. Diabetes is probably the most frequent cause of neuropathy. However it does not constitute a single nosological entity but is comprised of a variety of clinical and morphological changes. These are considered to be the consequences of metabolic derangements resulting from chronic hyperglycemia. Distal symmetrical neuropathies, which are most common, are characterized by axonal degeneration and segmental demyelination with loss of nerve fibres and fibrosis. Remyelination and axonal sprouting occur. Microvascular changes consist of thickening and hyalinization of the walls of the vessels. On electron microscopy these vessels appear thickened and show reduplication of the basal lamina that surrounds the endothelial cells and pericytes. The morphological bases of proximal symmetrical motor neuropathy, as well as of focal and multifocal neuropathies are briefly described. The synopsis of current knowledge can be helpful in diagnosis and differential diagnosis of disorders of the peripheral nervous system.