In healthy, middle-aged men, blood glucose measured 60 minutes after an oral glucose tolerance test better predicted cardiovascular morbidity and mortality than a 2-hour glucose value or fasting blood glucose measurements, according to findings published in the European Journal of Endocrinology.
“Fasting blood glucose (FBG) alone is not sufficient in predicting hyperglycemia-related mortality, while the standard 2-hour postload glucose value enables detection of subjects with impaired glucose tolerance, who have a significantly increased risk of death,” Mette L. Nielsen, a doctoral student in the cardiovascular and metabolic preventive clinic, Center for Individualized Medicine in Arterial Diseases, Odense University Hospital, Denmark, and colleagues wrote. “Furthermore, in overweight subjects with IGT, intensive lifestyle intervention and pharmacological treatment can prevent progression into overt type 2 diabetes and possibly ameliorate the risk of related cardiovascular complications. However, the 2-hour OGTT has low sensitivity, has non-optimal specificity for incident diabetes, and is time-consuming, and thus it is considered to carry limited cost-effectiveness and practicality.”
Nielsen and colleagues analyzed data from 4,934 men without known diabetes or previous CVD participating in the Malmö Preventive Project, a population-based cohort study including prespecified birth cohorts (median age, 48 years; mean BMI, 24.8 kg/m²; mean systolic blood pressure, 130 mm Hg). Participants underwent a 2-hour OGTT, with blood glucose levels determined at 0, 20, 40, 60, 90 and 120 minutes. Researchers followed the cohort from baseline screening until the date of myocardial infarction, stroke or death up to 27 years. Data on CV events and death were obtained from national registries.
Among men with normal glucose tolerance (n = 4,633), mean FBG was 4.6 mmol/L, mean 1-hour postload glucose value was 7.9 mmol/L and mean 2-hour postload glucose value was 5.1 mmol/L. Among men with IGT, mean FBG was 5 mmol/L, mean 1-hour postload glucose value was 10.6 mmol/L and mean 2-hour postload glucose value was 8.7 mmol/L. During follow-up, researchers observed 1,381 CV events, or 12.3 per 1,000 person-years, and 1,517 participants died from any cause. A final Cox regression model included age, active smoking, BMI, systolic BP, total cholesterol, triglycerides and creatinine in a clinical prediction model, which performed better than isolated blood glucose measurements for the prediction of all endpoints, according to researchers.
At 27 years, the 1-hour glucose value was a predictor of fatal MI (HR = 1.22; 95% CI, 1.09-1.36), nonfatal MI (HR = 1.1; 95% CI, 1.02-1.18) nonfatal-plus-fatal MI (HR = 1.13; 95% CI, 1.06-1.2), nonfatal-plus-fatal stroke (HR = 1.14; 95% CI, 1.06-1.24), nonfatal stroke (HR = 1.14; 95% CI, 1.05-1.24), any CV death (HR = 1.21; 95% CI, 1.14-1.28 and all-cause mortality (HR = 1.18; 95% CI, 1.14-1.23). FBG and the 2-hour postload glucose value did not independently predict any endpoints, according to researchers. At 20-year follow-up, the 2-hour postload value independently predicted CV death (HR = 1.13; 95% CI, 1.02-1.25); however, FBG still did not predict any endpoints (P for all < .21) and the 1-hour postload glucose value remained superior to both (P < .0001).
The clinical prediction model with added 1-hour postload glucose value performed better than clinical risk factors alone in predicting CV (likelihood-ratio test, P = .02) and all-cause mortality (likelihood-ratio test, P = .0001), according to researchers.
The researchers noted that the association between the 2-hour postload value and CV death was only evident on supplementary analyses with a shorter follow-up time.
“The predictive capacity might have been diluted over time, given the old age, comorbidity status and age-related events at the time of study completion,” the researchers wrote. “An additional explanation may be our relatively healthy (from a gluco-metabolic perspective) cohort, in which both fasting and 2-hour glucose values generally were low and rarely reached the criteria for prediabetes.” – by Regina Schaffer
Disclosures: This study was funded by a research grant from the Heart and Lung Foundation of Sweden and the Danish Diabetes Academy, supported by the Novo Nordisk Foundation.