title: Correlations between A1c, fasting glucose, 2h postload glucose, and β-cell function in the Chinese population.
abstract: This study was aimed to assess the associations of hemoglobin A1c (HbA1c), fasting plasma glucose (FPG), and 2h postload plasma glucose (2hPG) with β-cell function in the Chinese population. A total of 913 subjects underwent 75-g oral glucose tolerance test (OGTT) and HbA1c testing. According to OGTT, isolated impaired fasting glucose (i-IFG) was defined as 5.6 mmol/l ≤ FPG < 7.0 mmol/l and 2hPG < 7.8 mmol/l; isolated impaired glucose tolerance (i-IGT) was defined as FPG < 5.6 mmol/l and 7.8 mmol/l ≤ 2hPG < 11.1 mmol/l. HbA1c 5.7-6.4 % was used to identify subjects with prediabetes. Insulin release was calculated by basal homeostasis model assessment of insulin secretion (HOMA-β), early-phase InsAUC30/GluAUC30, and total-phase InsAUC120/GluAUC120. β-cell function relative to insulin sensitivity was expressed as disposition index (DI). All indices of insulin sensitivity and β-cell function gradually decreased with increasing HbA1c, FPG, and 2hPG (all p < 0.01). β-cell function decreased precipitously when HbA1c exceeded 5.5 %. Compared with HbA1c, FPG showed stronger correlations with HOMA-β, InsAUC30/GluAUC30, InsAUC120/GluAUC120, DI30, and DI120 (all p < 0.05), and 2hPG was more closely related to DI30 and DI120 (all p < 0.01). Moreover, FPG was more strongly related to HOMA-β and InsAUC30/GluAUC30 than 2hPG (all p < 0.05). The combination of i-IFG and HbA1c 5.7-6.4 % showed the greatest reduction in DI30 and DI120 compared with HbA1c 5.7-6.4 % alone, i-IGT, or i-IFG (p < 0.05). In conclusion, HbA1c could be used as a marker to identify subjects with impaired β-cell function, but OGTT performs better than HbA1c. The combination of HbA1c and FPG is a simple and sensitive method to evaluate β-cell function.
authors.affiliation: Department of Endocrinology, Drum Tower Hospital Affiliated to Nanjing University School of Medicine, Nanjing, 210008, China.
authors.forename: Cuiliu
authors.initials: C
authors.lastname: Li
authors.forename: Huijie
authors.initials: H
authors.lastname: Yang
authors.forename: Guoyu
authors.initials: G
authors.lastname: Tong
authors.forename: Shanmei
authors.initials: S
authors.lastname: Shen
authors.forename: Wenhuan
authors.initials: W
authors.lastname: Feng
authors.forename: Yan
authors.initials: Y
authors.lastname: Bi
authors.forename: Dalong
authors.initials: D
authors.lastname: Zhu
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People; D002681:China; D003430:Cross-Sectional Studies; D005215:Fasting / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D008297:Male; D008875:Middle Aged
chemical_list: D005947:Glucose; D006442:Glycated Hemoglobin; D007328:Insulin