Ageing and type 2 diabetes in an elderly Chinese population: the role of insulin resistance and beta cell dysfunction.

OBJECTIVE The aim of this longitudinal study was to examine the effects of ageing on glucose regulation in elderly Chinese men and women. SUBJECTS AND METHODS A total of 4,566 older Chinese men and women (mean age: 70.4 ± 6.7 years) were enrolled in the study. Oral glucose tolerance tests were performed in all participants at baseline and in 3,174 individuals (69.5%) after 3 years of follow-up. Insulin resistance and beta cell function were estimated by the homeostasis model assessment for insulin resistance (HOMA-IR) and beta function (HOMA%-b), respectively. RESULTS At baseline, 1,143 had type 2 diabetes (T2D), 517 had prediabetes and 2,906 had normal glucose tolerance (NGT). After 3 years of follow-up, 769 (42.2%) of 1,821 individuals with NGT at baseline progressed to prediabetes and 153 (8.4%) progressed to T2D. Of individuals with prediabetes at baseline, 17.3% progressed to T2D. In individuals who maintained NGT during follow-up ageing was associated with increased insulin resistance (p ≤ 0.001) and a compensatory increase in beta function (p ≤ 0.001). Individuals with NGT or prediabetes who progressed to T2D during follow-up had a significantly increased insulin resistance and a decreased beta cell function (p < 0.01). In contrast, individuals who regressed from prediabetes to NGT increased both insulin resistance and beta cell function (p < 0.01). CONCLUSIONS Ageing is associated with development of insulin resistance in an Elderly Chinese population. Therefore, maintenance of normal glucose regulation depends on the ability to compensatory increase of the beta cell function.