Cardiovascular risk in patients with fasting blood glucose levels within normal range

Fasting glucose levels elevated beyond the normal range have been associated with increased cardiovascular risk. However, it is unknown whether this association exists for variations of fasting glucose within the normal range. The present study was conducted using the computerized database of the Sharon-Shomron District of Clalit Health Services. Included in the present study were subjects with fasting glucose levels within the normal range (<100 mg/dl). We excluded patients with a history of cardiovascular disease or diabetes. The primary outcome was the incidence of coronary revascularization with either percutaneous coronary intervention or coronary artery bypass grafting. The 28,263 participants (age 53.7 ± 12.2 years) were divided into quartiles according to the fasting glucose level (75.4 ± 4.5, 83.6 ± 1.7, 88.9 ± 1.4, and 95.1 ± 2.2 mg/dl). During a mean follow-up of 5.9 ± 0.7 years, 424 subjects required coronary revascularization. A progressive increase was seen in the risk of coronary revascularization as the fasting glucose levels increased within the normal range (hazard ratio 1.73, 95% confidence interval 1.3 to 2.3, p >0.001, between the fourth and first quartiles). However, this association lost its statistical significance after adjustments for the conventional coronary risk factors (hazard ratio 1.17, 95% confidence interval 0.85 to 1.62, p = 0.328). In conclusion, elevated fasting glucose levels within the normal range were associated with an increased cardiovascular risk. This association was caused by the greater prevalence of the other conventional risk factors and not by the glucose level itself.