Objective: To evaluate the effect of lowering the fasting plasma glucose (FPG) cutoff point for the criterion of impaired fasting glucose (IFG) in the 2003 ADA guideline on the prevalence of IFG and risk of ischemic cardiovascular diseases (ICVD) associated with IFG in Chinese population.
Method: A prospective study was carried out in 11 provinces from 1992 to 2003. The baseline survey was conducted according to the WHO-MONICA protocol for risk factor surveys. These subjects have been followed-up for coronary heart disease (CHD) and stroke since the baseline survey. The association between baseline FPG and ICVD (CHD and ischemic stroke) events in 30 378 subjects aged 35 - 64 years in the 10-year follow-up period was analyzed.
Results: (1) Lowering the criterion for diagnosing IFG to 5.55 mmol/L increased the prevalence of IFG from 6.9% to 21.6% in Chinese population aged 35 - 64 years. (2) As compared with the group of FPG less than 5.55 mmol/L, the prevalence of other traditional CVD risk factors increased in the FPG level of 5.55 - 6.05, 6.11 - 6.94 and 6.99 mmol/L or above. (3) Univariate analysis method showed that the 10-year accumulated incidence and relative risk for ICVD increased with the elevated baseline level of FPG. (4) After adjusting for age and other ICVD risk factors (including hypertension, lipid disorder, smoking and obesity) FPG level of 5.55 - 6.05 mmol/L showed an independently predictive value for ICVD in men (RR = 1.302, 95% CI = 1.021 - 1.660), but not in women (RR = 1.255, 95% CI = 0.887 - 1.776). Hypertension, low HDL-C, smoking (men) and central obesity (women) were more strongly associated with ICVD than glucose status.
Conclusions: The newly defined IFG criterion (FPG 5.55 - 6.94 mmol/L) increased the prevalence of IFG by more than 2 times in Chinese population aged 35 - 64 years. The 10-year accumulated incidence and relative risk for ICVD increased with the elevated baseline level of FPG. The predictive value of hyperglycemia for ICVD was weaker than that of other traditional risk factors. Comprehensive intervention for multiple risk factors clustering should be strengthened to reduce the overall risk of CVD.