Correlations between A1c, fasting glucose, 2h postload glucose, and [beta]-cell function in the Chinese population

Acta Diabetol (2014) 51:601608 DOI 10.1007/s00592-014-0563-5

ORIGINAL ARTICLE

Correlations between A1c, fasting glucose, 2h postload glucose, and b-cell function in the Chinese population

Cuiliu Li Huijie Yang Guoyu Tong

Shanmei Shen Wenhuan Feng Yan Bi

Dalong Zhu

Received: 21 October 2013 / Accepted: 27 January 2014 / Published online: 5 March 2014 Springer-Verlag Italia 2014

Abstract This study was aimed to assess the associations of hemoglobin A1c (HbA1c), fasting plasma glucose (FPG), and 2h postload plasma glucose (2hPG) with b-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 dened as 5.6 mmol/ l B FPG \ 7.0 mmol/l and 2hPG \ 7.8 mmol/l; isolated impaired glucose tolerance (i-IGT) was dened as

FPG \ 5.6 mmol/l and 7.8 mmol/l B 2hPG \ 11.1 mmol/l. HbA1c 5.76.4 % was used to identify subjects with prediabetes. Insulin release was calculated by basal homeostasis model assessment of insulin secretion (HOMA-b), early-phase InsAUC30/GluAUC30, and total-phase InsAUC120/GluAUC120. b-cell function relative to insulin sensitivity was expressed as disposition index (DI). All indices of insulin sensitivity and b-cell function gradually decreased with increasing HbA1c, FPG, and 2hPG (all p \ 0.01). b-cell function decreased precipitously when HbA1c exceeded 5.5 %. Compared with HbA1c,

FPG showed stronger correlations with HOMA-b, 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-b and InsAUC30/GluAUC30 than 2hPG (all p \ 0.05). The combination of i-IFG and

HbA1c 5.76.4 % showed the greatest reduction in DI30

and DI120 compared with HbA1c 5.76.4 % alone, i-IGT, or i-IFG (p \ 0.05). In conclusion, HbA1c could be used as a marker to identify subjects with impaired b-cell function, but OGTT performs better than HbA1c. The combination of HbA1c and FPG is a simple and sensitive method to evaluate b-cell function.

Keywords Beta cell function Hemoglobin A1c Fasting

plasma glucose 2h plasma glucose Type 2 diabetes

mellitus

Introduction

b-cell dysfunction and insulin resistance play an important role in the pathophysiology underlying the development of type 2 diabetes mellitus (T2DM). Evidences demonstrate that insulin resistance occurs 1020 years before the...