Simultaneous occurrence of diabetes mellitus and juvenile dermatomyositis: report of two cases.

The simultaneous occurrence of juvenile dermatomyositis (DMS) and diabetes mellitus is described in 2 pediatric patients. Both these patients presented with significant weight loss, polyuria, and polydypsia within a short time of being diagnosed with JDMS, while these patients were taking oral prednisone (40-60 mg/day in divided doses). Laboratory evaluation detected ketonuria, significant hyperglycemia (696 and 913 mg/dL) and low serum levels of insulin and C-peptide. Both these patients were treated with high doses of insulin. Islet cell and GAD65 antibodies were found to be positive in 1 of the patients, pointing toward a diagnosis of insulin-dependent diabetes mellitus. The other patient tested negative for these antibodies and required insulin therapy for approximately 6 months. Steroid-induced diabetes mellitus seemed highly likely in this case. We hypothesize that a common environmental trigger possibly a viral infection might have been responsible in causing 2 different autoimmune pathologies in these genetically predisposed individuals.