Slowly progressive insulin-dependent diabetes mellitus associated with pernicious anemia.

A 59-year-old man was found to have diabetes mellitus five months after the diagnosis of pernicious anemia. Although the urinary C-peptide level corresponded to a non-insulin-dependent stage (39.9 microg/day), the markedly extremely elevated titers of GAD antibody suggested that this case very likely represented a non-insulin-dependent stage of slowly progressive insulin-dependent diabetes mellitus (SPIDDM). Because thyroid and adrenal functions were normal, this our case was not considered to be polyglandular autoimmune syndrome (PGAS). We report this case because patients with pernicious anemia and SPIDDM in the absence of PGAS are rare in Japan.