Background: Elevated fasting plasma glucose (FPG) levels within the diabetic or impaired fasting glucose range are associated with incident cardiovascular morbidity and mortality. However, it is not clear whether this association remains within the normal FPG range. We aimed to evaluate the association between FPG levels within the reference range and all-cause mortality and cardiovascular risk in non-diabetic women.
Methods: Included were women ≥40 years with FPG within the normal range. Patients with a history of cardiovascular diseases or diabetes were excluded. Primary endpoints included all-cause mortality and coronary revascularization.
Results: The 30,861 participants were stratified into 5 quintiles of FPG within the normal range. During a mean follow-up of 6.2±1.1 years, 2,637 (8.5%) participants died and 394 (1.2%) underwent coronary revascularization. Comparison of mortality risk according to quintiles of FPG demonstrated a J-shaped relationship with the lowest observed death rates in the FPG interval between 85-89mg/dl. This association remained significant following a multivariate adjustment with significantly higher mortality rates observed among patients in the lowest and highest quintiles of FPG within the normal range ( HR=1.25, 95CI=1.11-1.4, P<0.0001, and HR=1.18, 95CI=1.05-1.32, P=0.005, respectively). We observed a progressive increase in the risk for coronary revascularization as FPG was higher within the normal range. However, this association lost its statistical significance following a multivariate adjustment.
Conclusions: Both low and high FPG levels within the normal range are associated with increased all-cause mortality. Further investigation is needed for better understanding of this association before therapeutic recommendations can be made.
