Diabetic amyotrophy is a disabling illness that is distinct from other forms of diabetic neuropathy. It is characterized by weakness followed by wasting of pelvifemoral muscles, either unilaterally or bilaterally, with associated pain. Sensory impairment is minimal in the cutaneous distribution sharing the same root or peripheral nerve as affected musculature. Most commonly, the onset is in middle age or later, although it may occur in youth. A concomitant distal predominantly sensory neuropathy may be present. Electrodiagnostic studies are most often consistent with a neurogenic lesion attributable to a lumbosacral radiculopathy, plexopathy, or proximal crural neuropathy. The natural course of the illness is variable with gradual but often incomplete improvement. The site of the lesion and the pathogenesis of diabetic amyotrophy remain controversial. Recent studies suggest a role for immunomodulating agents in certain types of diabetic neuropathy, including diabetic amyotrophy.