Fig. 1

Classification of glycemic status by fasting glucose and two-hour post-load glucose levels. IFG only, impaired fasting glucose only, i.e., fasting level of 5.6–6.9 mmol/l and 2hPG < 7.8 mmol/l; IGT only, impaired glucose tolerance only, i.e., 2hPG level of 7.8–11.09 mmol/l and fasting glucose < 5.6 mmol/l, IFG + IGT, the presence of both impaired fasting glucose and impaired glucose tolerance, T2DM type 2 diabetes mellitus, i.e., fasting glucose ≥7.0 mmol/l or 2hPG ≥11.1 mmol/l; Known T2DM a history of self-reported physician-diagnosed diabetes or the use of glucose-lowering drugs regularly