Based on the 1997 and 2003 IFG definitions, the odds of developing coronary heart disease (CHD) among women with IFG in the 110 to 125 mg/dl (6.1 to 6.9 mmol/l) range approach the risk conferred by having diabetes. The 1997 IFG definition was associated with a statistically significant increased odds of developing cardiovascular disease (CVD) among women, whereas no increased odds were observed in men for either IFG definition. For diabetes, the 1997 IFG definition is associated with a greater risk of developing diabetes compared with the 2003 IFG definition. In a study conducted by Levitsky et al, women with FPG 110 to 125 mg/dl (6.1 to 6.9 mmol/l) are at significantly increased risk of both CHD and CVD.
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According to Levitsky et al, there are conflicting data regarding the effect of impaired fasting glucose on cardiovascular risk. Several studies have found that the 1997 IFG definition is associated with significantly increased risk for CVD, while some have shown no significantly increased risk. To date, very few studies exist which have evaluated the 2003 IFG cut-point and its ability to predict CVD, and none have demonstrated an increased risk.
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Data from the Heart and Estrogen/Progestin Replacement Study enrolled women with known coronary disease based on their fasting glucose status. The study followed them for CVD events, stroke, transient ischemic attacks and congestive heart failure hospitalization for an average of 6.8 years.
16 Kanaya et al reviewed this data and found that women with FPG 100 to 125 mg/dl (5.6 to 6.9 mmol/l) were at no increased risk for any end point as compared with women with normal levels of fasting glucose.
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Similarly, Levitzky et al found that women categorized by the 2003 IFG definition did not have a statistically significant increased risk of CVD (OR 1.4, 95% CI 0.9 to 2.1). However, they did have significantly increased odds of CHD (OR 1.7, 95% CI 1.0 to 3.0, p = 0.048). This difference could have been due to the differences between the study samples. Only individuals free of CVD at baseline were included in the study by Levitsky et al. Whereas, Kanaya et al used a sample of women with pre-existing CVD, and followed their participants for new events.
Finally, a recent study by Kim et al examined CVD risk factor prevalence and prevalent CVD events among individuals based on the 1997 and the 2003 IFG definition. The study found that the 2003 definition was not associated with an elevated level of CVD risk factors or CVD as compared to the 1997 definition.
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Several of these studies have found that women had greater odds of CHD and CVD as compared with men. However, men have greater absolute event rates for cardiovascular disease. A recent meta-analysis that included approximately 33,000 women and 172,000 men, examined the potential of IFG as a risk factor for CVD. Once again, results demonstrated that the risk of CVD events was markedly greater in cohorts that included women.
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