Revising the fasting glucose threshold for detection of cardiovascular risk factors: analysing two representative population-based studies of more than 50,000 Iranians in 3 years: The National Survey of Risk Factors for Non-Communicable Diseases of Iran.

OBJECTIVES

To study the prevalence of cardiovascular risk factors across different glycaemia strata and to assess the optimal cut-off value of fasting plasma glucose (FPG) to identify the constellation of cardiovascular risk factors.

METHODS

Data of the National Survey of Risk Factors for Non-Communicable Diseases of Iran (SURFNCD 2005-2007) were analysed. Prevalence rates of obesity, central obesity, hypertension and hypercholesterolemia of individuals with Impaired Fasting Glucose (IFG) were compared with those of individuals with normal fasting glycaemia and newly diagnosed diabetes. Optimal FPG cut-point to diagnose subjects with cardiovascular risk factors was assessed.

RESULTS

Prevalence of each and combinations of cardiovascular risk factors were higher among subjects with IFG compared to those with normal fasting glycaemia. The areas under the curve (AUC) for detecting cardiovascular risk were highest at FPG values of 90 mg/dL. FPG of 90 mg/dL was the optimal cut-off and, in comparison to 100 mg/dL, corresponds to correct detection of 26-29% of obese, 22-27% of centrally obese, 26-29% of hypertensive and 25-30% of hypercholesterolemic individuals.

CONCLUSIONS

IFG and even lower levels of FPG are associated with high prevalence of cardiovascular risk factors in Iranian adults. This study suggests the FPG cut-off to be revised at 90 mg/dL to identify people with increased cardiovascular risk.