Evaluation Of β-cell Function By MMTT And OGTT In Obese Children And Adolescents With Metabolic Syndrome

BackgroundsMetabolic syndrome is a set of clinical comprehensive syndrome closely related to life style characterized by obesity, hyperglycemia, hypertension and dyslipidemia. Obese children with metabolic syndrome (MS) or component metabolic disorders (cMD) are at high risk of developing T2DM and CVD, and constitute the main pool of adult T2DM. In the setting of insulin resistance, progressive β-cell dysfunction is especially important in the process of the onset and progression of diabetes. However, data are very limited for evaluating β-cell function in youth with MS or cMD.ObjectiveTo evaluate islet β-cell function during the liquid mixed-meal test (MMTT) and oral glucose tolerance test (OGTT) in obese children and adolescents with clinical diagnosis of MS, cMD, or iOB(isolated obesity) to provide a reference for clinical interventions and early prevention.MethodsWe prospectively designed three groups of participants for study:metabolic syndrome (MS), component metabolic disorders (cMD) and isolated obesity (iOB), clinically data from obese children and adolescents (50 iOB,72 cMD, and 59 MS) between May,2013, and May,2015 were obtained. All of the participants underwent MMTT and OGTT, and indices of insulin secretory function and insulin sensitivity were calculated for study.ResultsCompared to the cMD and iOB groups, participants in the MS group had significantly lower HDL-C (P<.001) and greater body mass index (BMI) (P<.01) and waist circumference (P<.001), and had higher SBP (P<.001), DBP (P<.001),2h glucose (P<.001), IF (P<.001), TG (P<.001), and non-HDL-C (P<.001). Islet β-cell function relative to area under curve C-peptide (CP) at 120 minutes (AUC CP120, 900.3±32.20 ng/mL.min vs.769.97±33.47ng/mL.min,P=.007) and peak CP (10.02±0.39 ng/dL vs. 8.44±0.40 ng/dL, P=.007) derived from MMTT were significantly higher in the MS group compared with the iOB group both before and after adjusting for BMI. The MS group had higher homeostasis model assessment for insulin secretion (HOMA-β%) compared with the cMD and iOB groups after adjusting for BMI (P-.036, P=.008). However, there was no difference between the cMD and iOB groups in AUC CP120, peak CP, and HOMA-β%. The insulinogenic index at 30 minutes and oral disposition index derived from OGTT were not different among the three groups. After controlling for BMI, the MS group had higher HOMA for insulin resistance (P=.017, P=.000) and lower 1/(fasting CP) (P=.034, P=.011) compared with the cMD and iOB groups, and the iOB group had higher quantitative insulin sensitivity index (QUICKI) (P=.000, P=.018) and oral glucose insulin sensitivity (OGIS) (P=.000, P=.004) compared with the MS and cMD groups.ConclusionCompared with iOB children, there were no signs of defects of early phase insulin secretion in MS and cMD children, indicating that youth with MS and cMD still had significant pancreatic reserve in response to their severe insulin resistance, offering a window in time for intervention before development of diabetes.