Prevalence of glutamic acid decarboxylase antibodies amongst young Malaysian diabetics

This study determined the prevalence of glutamic acid decarboxylase antibod ies (GAD Ab) in a group of 926 young Malaysian diabetics of three ethnic gr oups, Malay, Chinese, and Indian. Patients were clinically diagnosed to be Type 1 or Type 2 before the age of 40 years. The overall GAD Ab positivity was 17.4% (161/926), significantly higher in the Type 1 than the Type 2 dia betics (35.5%, 116/329 vs. 7.5%, 45/597, P = 0.0001). Compared to GAD Ab ne gative patients, seropositive diabetics were diagnosed at younger age (21.2 +/- 0.9 vs. 27.4 +/- 0.3 y, P = 0.0001), had lower fasting (289 +/- 27.4 v s. 640 +/- 17.6 pmol/l, P = 0.0001) and post-glucagon C-peptide levels (527 +/- 51.8 vs. 1030 +/- 28.9 pmol/l, P = 0.0001). There were no racial diffe rences in the prevalence of GAD Ab; of the total Type 1, 30.8, 36.4, and 39 .4% were Malay, Chinese, and Indian diabetics, respectively and of the tota l Type 2, 8.8, 8.2, and 4.4% were Malay, Chinese, and Indian diabetics resp ectively. There was a curvilinear relationship between GAD Ab and the post- glucagon C-peptide levels, suggesting that GAD Ab do play a role in the bet a-cells destruction and could be an important immune marker for the LADA gr oup. This study reconfirmed previous reports that the autoimmune mechanisms in the Type 1 Asian diabetics are indeed different from the Caucasians, an d further investigations should be carried out to explain the differences. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.