Pancreatic islet-cell antibody as a marker for asymptomatic and latent diabetes and prediabetes.

Pancreatic islet-cell antibodies (I.C.Ab) were detected in 31 patients with organ-specific autoimmune disorders, 4 first-degree relatives of I.C.Ab-positive diabetics, and 1 apparently normal subject, none of whom had clinical evidence of diabetes. 10 of these 36 subjects were found to have diabetic glucose-tolerance tests (G.T.T.S), 4 had lag storage, and 22 had normal G.T.T.S.2 had latent diabetes, as evidenced by diabetic G.T.T.S during pregnancy and thyrotoxicosis; another 2 subsequently developed insulin-dependent diabetes (I.D.D.) Serum from 26 subjects had been stored for 1-11 yr before the G.T.T.S were done. The titres in some were shown to rise and fall over the years, while in others they remained remarkably constant. There was no correlation between the titre, change in titre or the duration of I.C.Ab or the presence of HLA-B8, BW15, or CW3 and the result of the G.T.T. In addition to acting as a marker for asymptomatic and latent diabetes and prediabetes, it seems that the presence of I.C.Ab in the serum may define a new group of potential diabetics with normal G.T.T.S. Many such subjects have one or more organ-specific autoimmune disorders (irrespective of diabetic family history), but some are first-degree relatives of I.C.Ab-positive subjects (mainly I.D.D.). About 0-5% of the general population also have I.C.Ab in their serum.