A Study On Insulin Resistance And B Cell Function In Normal Glucose Tolerance First-degree Relatives Of Type 2 Diabetics

ObjectiveType 2 diabetes mellitus (T2DM) patients and first-degree relatives of patients with type 2 diabetes have a common genetic basis of diabetes, We investigate insulin resistance andβcell function in type 2 diabetes and nondiabetic first-degree relatives and to explore their roles in pathogenesis and development of diabetes mellitus.MethodsCollected from December 2006 to December 2007 first-degree relatives of patients with type 2 diabetes admitted in Shengjing Hospital and the healthy people without a family history of diabetes. both were given 75 g oral glucose tolerance test (OGTT). According to two OGTT results and 1999 WHO diagnostic standards, Choose 8 cases with family history of diabetes as normal control group (NC group ), 7 cases with normal glucose tolerance of T2DM relatives as NGT group, 10 cases with abnormal glucose tolerance of T2DM relatives as IGT group .Insulin resistance was measured using hyperinsulin-euglycemic clamp ,and beta-cell function was assessed by intraveneous glucose tolerance test.Results1,Insulin resistanceAll non-diabetic first-relatives of type 2 diabetic patients have insulin resistance, GIR in the NGT group with normal glucose tolerance and IGT group with impaired glucose tolerance were significantly lower than those in NC group without a family history of diabetes (6.80±0.90 vs 10.22±1.07, P <0.05, 6.69±1.16 vs 10.22±1.07, P <0.05). Regardless of the existence of abnormal glucose tolerance, insulin resistance in first-relatives is the same as the level of (6.80±0.90 vs 6.69±1.16, P = 0.62).2,B islet cell functionB-cell function is normal when glucose tolerance is normal. There was no significant difference in insulin secretion of first- phase and second-phase no matter the NGT group of family history of diabetes or the NC group without diabetes family history (first- phase 29.63±6.15 vs 49.5±9.26, P = 0.65 . second-phase 14.61±1.62 vs 19.66±1.96, P = 0.96). When changes occurs in glucose tolerance (IGT), islet cell B function decreased significantly. Compared with the NGT group of a family history of diabetes and the NC group without a family history of diabetes, insulin secretion of first- phase and second-phase in decreased significantly (23.83±8.54, 12.07±2.40 vs 29.63±6.15,14.61±1.62 vs 49.59±9.26, 19.66±1.96 P <0.05).ConclusionThe first-degree relatives of T2DM who are predispose to diabetes have insulin resistance before plasma glucose changed. And impaired glucose metabolism was secondary to impaired B cell function.