Abstract
The degree of concordance for NIDDM is higher than that for IDDM even though twins are almost always living apart when diabetes is diagnosed. We report a case of anti-GAD discordance in identical twin sisters with aged onset diabetes.
A 78-year-old woman seen in June 14, 1999, was diagnosed with diabetes mellitus (DM) and treated with oral hypoglycemic agent (OHA). Her blood glucose control recovered slightly and her HbAic fell from 10.4 % to 8.3%.Despite the relatively high 01-IA dose of 3.75mg/day of glibenclamide, HbAic rose to 10.3%, showing high anti-GAD titer of 748.0U/ml. We were informed then that she had an elder identical twin sister.Insulin treatment was started and her HbAic fell to 6.8%.The elder sister, living in Hiroshima, had been diagnosed with DM 10 years ago and treated with OHA.Her HbAic was 7.4% and her anti-GAD negative when she was seen at 80 years of age.These patients had HLA DRB 1*1101-DQA 1*0505-DQB 1* 0301, a well-known protective haplotype for type 1 diabetes.No mitochondrial DNA A 3243 G mutation was detected in either twin.
