To determine whether diabetes defined by isolated postchallenge hyperglycemia (IPH) (2-h postchallenge plasma glucose ≥ 11.1 mmol/l with fasting plasma glucose [FPG] < 7.0 mmol/l) increases the risk of fatal cardiovascular disease (CVD) in older women and men.
In a prospective study, we followed 769 men and 1,089 women, aged 50–89 years, who had no history of diabetes or myocardial infarction and demonstrated no fasting hyperglycemia (i.e., FPG < 7.0 mmol/l) when they underwent oral glucose tolerance testing at baseline in 1984–1987.
At baseline, 70% of 125 women and 48% of 133 men with previously undiagnosed diabetes had IPH. Over the next 7 years, women with IPH had a significantly increased risk of fatal CVD and heart disease compared with nondiabetic women. This increased risk was not observed in men with IPH. This association was independent of age, hypertension, central obesity, cigarette smoking, HDL cholesterol, and triglycerides (multiply adjusted hazard ratio and 95% CI: 2.6 and 1.4–4.7 for CVD; 2.9 and 1.3–6.4 for heart disease).
Diabetes defined by IPH alone is common in older adults and more than doubles the risk of fatal CVD and heart disease in older women. Because the prevalence of IPH increases with age, the use of fasting glucose alone for diabetes screening or diagnosis may fail to identify most older adults at high risk for CVD and should be reevaluated.