ABSTRACT
OBJECTIVES: To compare the pancreatic ß-cell functions of Han people between those with normal glucose tolerance (NGT),prediabetes (PD),and newly-diagnosed type 2 diabetes mellitus (NDDM), and to evaluate the value of the continuous glucose monitoring system (CGMS) in determining ß-cell functions. METHODS: A total of 169 volunteers of Han people (20-75 years old, 72 male and 97 female) without diagnosed diabetes were given 75-g oral glucose tolerance test (OGTT) and insulin release tests. The body mass index (BMI) of the participants ranged from 18.5 to 28.0 kg/m².They were categorized into NGT (n=87), PD (n=52) and NDDM (n=30) groupsaccording to the World Health Organization (WHO) 1999 criteria.Blood samples were taken to test triglyceride(TG),total cholesterol (TC),and glycosylated hemoglobin A1c (HbA1c). The participants were also given a 72 h continuous glucose monitoring. The ß-cell functions were calculated using the OGTT and insulin release test results, which included homeostasis model assessment insulin resistance (HOMA-IR),homeostasis model assessment ß-cell function (HOMA-B),basic secretion, early phase secretion, and second phase secretion. The area under the curve of glucose (AUC-G) was estimated through the CGMS.A multivariate stepwise regression model was developed to identify predictors of ß-cell functions. RESULTS: Significant differences in age,BMI,HOMA-IR,HOMA-B,AUC-G, basic secretion, early phase secretion and second phase secretion were found between the NGT and PD groups (P<0.05) and between the NGT and NDDM groups (P<0.05). Differences in AUC-G and basic secretion and early phase secretion were found between the PD and NDDM groups (P<0.05),but not in age, BMI, HOMA-IR, HOMA-B, and second phase secretion.The multivariate stepwise regression analysis showed that HOMA-B (standardized partical regression coefficient ß=-0.244,P=0.001), basic secretion (ß=-0.355,P<0.001), and HbA1c (ß=0.638,P<0.001) contributed significantly to the AUC-G. CONCLUSIONS: ß-cell functions decline in those with prediabetes, which appears first at the second phase secretion. Changes in ß-cell secretion functions are more obvious than in insulin resistance during the progression from PD to NDDM.AUC-G can be a better indicator of impaired ß-cellfunctions.
