GLUTAMIC-ACID DECARBOXYLASE ANTIBODIES IN NON-INSULIN-DEPENDENT DIABETES PATIENTS WITH SECONDARY SULFONYLUREA FAILURE IN THAILAND

The objective of this study was to determine the frequency of glutamic acid decarboxylase antibody (GAD-Ab) in Thai non-insulin-dependent di abetes (NIDDM) patients who had secondary sulfonylurea failure. Sera w ere collected from 40 NIDDM patients, who had history of secondary fai lure to treatment with sulfonylurea, for analysis of fasting c-peptide and GAD-Ab, Both c-peptide and GAD-Ab were measured using radioimmuno assay method. Of 40 patients, ten (25.0%) were positive for GAD-Ab wit h a mean level of 59.9 U/ml (median 58.5, range 3.4-127). Patients wit h GAD-Ab(+) had a significantly lower fasting c-peptide levels than th ose with GAD-Ab(-) albeit shorter duration of diabetes (0.21 +/- 0.19 (S.D.) versus 0.52 +/- 0.33 nmol/l; P = 0.003). Duration of treatment with sulfonylurea in patients with GAD-Ab(+) was also shorter (4.6 +/- 3.5 versus 10.4 +/- 5.5 years; P = 0.001). Age at onset of diabetes d id not differ between these two groups. Among 40% of patients who had insulin deficiency (fasting c-peptide level < 0.33 nmol/l), GAD-Ab was present in half and these GAD-Ab(+) patients had significantly shorte r duration of sulfonylurea treatment (3.3 +/- 2.3 versus 10.0 +/- 7.9 years; P = 0.018). In conclusion, the frequency of GAD-Ab in Thai NIDD M patients with secondary sulfonylurea failure in this study was 25%, Almost all GAD-Ab(+) patients had insulin deficiency and most had been initially treated with sulfonylurea for a few years before depending on insulin. This group of patients represents a slowly progressive typ e I or latent autoimmune diabetes in adult diabetic population. (C) 19 97 Elsevier Science Ireland Ltd.