ABSTRACT
Oral glucose tolerance test(OGTT)was performed in 419 first-degree relatives(FDRs)of type 1 diabetes mellitus. GADA, IA-2A, and IAA were determined by radioligand assay, and the positive rates were 7.16%, 1.43%, and 1.26%, respectively. Intravenous glucose tolerance test(IVGTT)and nateglinide-OGTT were performed in 39 controls, 11 first-degree relatives with positive autoantibody(Ab+group), 14 ones with negative autoantibody(Ab-group)during 5-7 days.The first-phase insulin release(FPIR), area under insulin release during 0-10 min [AUC0-10] of IVGTT and the value of(ΔI30/ΔG30)of nateglinide-OGTT in Ab+group were lower than those of control and(2.75±0.37 vs 3.61±1.05)mU/mmol, all P＜0.05]. The 1st min insulin release in Ab+group was lower than that of Ab-group [(3.80±0.30 vs 4.52±0.70)mU/L, P＜0.05]. The HOMA-IR was higher in Ab-group than that in control group(2.92±1.04 vs 1.96±1.22, P＜0.05). The results suggest that the positivity rates of autoantibodies in FDRs of type 1 diabetes mellitus are very close to those of Caucasian. There exist insulin secretion defects in FDRs with positive autoantibody while insulin resistance in FDRs with negative autoantibody.