Abstract:

Objective To evaluate the insulin resistance and beta-cell function under different glucose tolerance status in firstdegree relatives of type 2 diabetes pedigree. Methods Four hundred and forty first-degree relatives of type 2 diabetes pedigree were enrolled and divided into type 2 diabetes mellitus group (T2DM group, n=144), impaired glucose regulation group (IGR group, n=139) and normal glucose tolerance group (NGT group, n=157), and another 121 people without family history of diabetes mellitus, history of abnormal blood glucose and gestational diabetes were served as normal control group (NC group). All subjects underwent oral glucose tolerance tests and insulin releasing tests. Insulin sensitivity was estimated by homeostasis model assessment for insulin resistance (HOMA-IR) and insulin action index (IAI). Basic insulin secretion function index (HOMA-β), early insulin secretion function index (ΔI30/ΔG30), modified betacell function index (MBCI) and glucose disposition indices (DI) were used to evaluate the beta-cell function. Results IAI in T2DM group and IGR group were significantly lower than those in NGT group and NC group （P<0.05）, while HOMA-IR in T2DM group and IGR group were significantly higher than those in NGT group and NC group （P<0.05）. HOMA-IR in T2DM group was significantly higher than that in IGR group （P<0.05）. There was no significant difference in HOMA-IR and IAI between NGT group and NC group （P>0.05）. Comparison of parameters of beta-cell function revealed that progressive decrease was observed in each parameter from NC group, NGT group, IGR group and T2DM group, and there were significant differences in each parameter among groups （P<0.05）except for those in HOMA-β, MBCI and DI3 between NGT group and NC group. Conclusion No obvious insulin resistance is observed in first-degree relatives of type 2 diabetes pedigree with normal glucose tolerance, while there exists decrease in beta-cell function with early insulin secretion defect.

Key words: type 2 diabetes, first-degree relatives, insulin resistance, beta-cell function