Sciatic neuropathy is caused by a wide spectrum of etiologies including trauma, compression, metabolic, infectious, and inflammatory conditions. Diabetic mononeuropathy remains one of the more elusive disease manifestations due to lack of large-scale prevalence studies and varied classification schemes. In this study, we present the case of a 48-year-old female diagnosed with diabetic mononeuropathy involving the sciatic nerve. Electromyography and nerve condition studies showed left sciatic neuropathy, and magnetic resonance imaging of the pelvis revealed an elarged left sciatic nerve. The patient was managed by controlling the blood glucose level and by therapeutic exercise. This case aims to achieve a better understanding of mononeuropathies occuring in diabetes.