INSULIN AUTOANTIBODIES BEFORE AND AFTER CARBIMAZOLE THERAPY IN ASIAN INDIAN PATIENTS WITH GRAVES-DISEASE

Carbimazole therapy can induce insulin autoantibodies (IAA) in Japanes e Graves' disease patients, a phenomenon possibly linked to their immu nogenetic profile. This phenomenon is not observed in Caucasians. We a ssessed IAA levels in 114 North Indian Graves' disease patients before and after carbimazole therapy (mean duration 6.2 +/- 3.9 months). The functional significance of IAA was assessed in 46 of them by first ph ase (sum of +1 and +3 min) insulin response to intravenous glucose (IV GTT) and an oral glucose tolerance test (OGTT) undertaken before comme ncement of the carbimazole therapy. IAA were measured using a radiobin ding assay and expressed as the assay precision unit, S.D. scores (S.D .S), over healthy controls. Before treatment 22 of 114 (19.3%) patient s were IAA positive (mean +/- S.D., 5.9 +/- 3.2 S,D.S). After carbimaz ole therapy a further 11 (9.6%) showed positive for IAA (mean +/- S.D. , 3.5 +/- 1 S.D.S). Of the 22 patients who were IAA positive before tr eatment, 12 became negative after carbimazole therapy. The fasting ins ulin and first phase insulin responses were similar in IAA positive an d IAA negative Graves' disease patients (mean +/- S.D., 61.7 +/- 35.9 versus 88.3 +/- 46.6 pmol/l, P = 0.123 and 1127 +/- 696 versus 1033 +/ - 430 pmol/l, P = 0.716, respectively). The OGTT results were comparab le in the IAA positive and the IAA negative groups. Thus, North Indian Graves' disease patients, who resemble Caucasians in their HLA haplot ypes, behave like Japanese in their tendency to become IAA positive wi th carbimazole therapy. A subset of the patients who were IAA positive before treatment also demonstrated negative IAA (12/22) after carbima zole therapy. (C) 1995 Elsevier Science Ireland Ltd. All rights reserv ed.