The distributive characteristics of impaired glucose metabolism subcategories in Chinese adult population

Objective: To clarify the frequencies and clinical features of different impaired glucose metabolism subcategories in Chinese adults.

Methods: A cross-sectional analysis of the data of 15,637 Chinese adults (aged >or= 25 years) who underwent standard 75 g oral glucose tolerance test from the National Diabetes Mellitus Survey (1994) was conducted. According to the 1999 WHO criteria for diabetes, the subjects were divided into 7 groups: normal glucose tolerance (NGT, FPG < 6.1 mmol/L and PG 2 h < 7.8 mmol/L), isolated impaired fasting glucose (i-IFG, 6.1 or= 7.0 mmol/L and PG 2 h < 11.1 mmol/L), isolated postload hyperglycemia (IPH, FPG < 7.0 mmol/L and PG 2 h >or= 11.1 mmol/L), and combined IFH and IPH (IFH/IPH, FPG >or= 7.0 mmol/L and PG 2 h >or= 11.1 mmol/L). The frequencies of the above subcategories were calculated and the clinical characteristics were compared.

Results: (1) The frequencies of NGT, i-IFG, i-IGT, IFG/IGT, IFG, IPH, and IFH/IPH were 50.8%, 8.8%, 12.3%, 6.1%, 6.4%, 5.2%, and 10.4% respectively. (2) The frequencies of i-IGT, IFG/IGT, IPH, and IFH/IPH increased with age, whereas the frequencies of i-IFG and IFH tended to plateau in the age groups of 25 - 34 years and 55 - 64 years. (3) The mean age and blood pressure were significantly lower in the i-IFG group (vs the i-IGT or IFG/IGT group) and the IFH group (vs IPH or IFH/IPH group). Compared with the IPH group, the IFH group had higher homeostasis model assessment (HOMA) insulin resistance index (HOMA-IR) and lower beta cell function index (BCI).

Conclusions: i-IGT is the most common impaired glucose regulation (IGR) subcategory, and IFH/IPH is the most common diabetes subcategory in Chinese adults. The frequencies of i-IGT and IFH/IPH increase with age. The clinical features of i-IFG (IFG) are greatly different from those of i-IGT (IPH), suggesting that the determinants of FPG and PG 2 h differ.