Multiple antibody status in type 1 diabetic patients and subjects at various risk with islet-cell antibodies

The frequency of 37/40 kD antibodies and their association with other pancreatic humoral markers were studied in 109 recently diagnosed Type 1 diabetic patients and 116 subjects with islet-cell antibodies (ICA) at various risk for this disease (64 relatives of Type 1 diabetic patients, 23 schoolchildren with no family history of diabetes, and 29 patients with Graves' disease). At the time of diagnosis, 37/40 kD antibodies were detected in 45% of Type 1a and 77% of Type 1b diabetic patients (p = 0.03). Antibodies to glutamic acid decarboxylase (GAD) and/or 37/40 kD were present with the same frequency as ICA (86%). The frequency of 37/40 kD antibodies was not significantly different between the 3 groups at risk, in contrast with GAD antibodies which were found at a lower frequency in schoolchildren (p < 0.02). Frequencies of other pancreatic markers (ICA cross-reactive with mouse pancreas and insulin autoantibodies) and the combination of ICA with at least two other markers were significantly higher in relatives than in the other groups at risk (p < 0.02). Out of 116 ICA-positive non-diabetic subjects, 10 developed diabetes. All 10 displayed 37/40kD and/or GAD antibodies during the prediabetic phase. In 8 of these 10 patients, ICA was combined with at least two other markers, whereas this association was detected in only 17 of the remaining 106 subjects who did not progress to diabetes (p < 10(-4). Thus, 37/40 kD antibodies were found in about half of Type 1 diabetic patients, and with a higher-frequency in Type 1b than 1a. In ICA-positive non-diabetic subjects, our date confirm that a combination of multiple antibodies, including GAD antibodies and 37/40 kD antibodies, can enhance the predictive value for diabetes. Comparison of ICA-positive relatives of diabetic patients, schoolchildren and patients with Graves' disease revealed distinct frequencies and combinations of markers of diabetes. This might reflect different patterns of progression among these 3 groups.