Necrotizing fasciitis is a rapidly spreading infection of the subcutaneous tissue and fascia; diabetes mellitus appears to be the most frequent underlying disease. Early diagnosis and immediate aggressive surgical therapy are paramount to curtail morbidity and mortality, but diagnosis is often difficult and unnecessarily delayed. We describe a case of necrotizing fasciitis precipitating diabetic ketoacidotic coma where correct diagnosis was not made until the 14th hospital day. We stress the fact that physicians caring for critically ill patients should be keenly aware of the possibility of necrotizing fasciitis when tending diabetic patients with unexplained fever; failure to recognize the disease can have devastating results. Finally, we believe this to be the first reported case of diabetic ketoacidotic coma precipitated by necrotizing fasciitis.