Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) may occur in association with diabetes mellitus (DM). We report a case of a poorly controlled diabetic patient who presented with rapid onset of bilateral lower extremity weakness and sensory loss associated with sacral and posterior thigh paresthesias and urinary and bowel incontinence, indicative of cauda equina syndrome (CES). Subsequent evaluation was consistent with CIDP. Monthly infusions with intravenous immunoglobulins (IVIg) with strict glycemic control using insulin resulted in remarkable clinical and electrophysiological recovery. This case report describes a rare presentation of CIDP and emphasizes the importance of early utility of electrodiagnostic (EDX) studies in the clinical evaluation of diabetic patients presenting with rapidly progressive lower extremity weakness and sensory loss associated with diminished reflexes. © 2007 Elsevier B.V. All rights reserved.