Elevated blood glucose readings at 1 hour provide better risk stratification for type 2 diabetes and associated cardiovascular complications than readings at 2 hours among middle-aged men, according to a prospective, population-based study published in Diabetes Care.
In this study, investigators prospectively evaluated rates of type 2 diabetes in men who underwent blood glucose measurements at 0, 1, and 2 hours. The median age in this cohort was 48 years, and the median follow-up was 33 years.
During the follow-up period, a total of 636 (13%) men received a diagnosis of type 2 diabetes. Incident diabetes was associated with elevated 1-hour glucose levels (hazard ratio 3.40 [95% CI, 2.90-3.98], P <.001). Glucose readings at 1 hour offered greater risk assessment compared with impaired glucose tolerance (C index 0.637 vs 0.511, P <.001).
In patients categorized by fasting glucose, the use of the 1-hour glucose measurement offered better improvement in net reclassification than the 2-hour measurement (0.214 vs 0.016, respectively). According to the investigators, participants with elevated 1-hour glucose measurements also had higher risk for myocardial infarction, fatal ischemic heart disease, retinopathy, and peripheral vascular complications.
Considering that the definition of diabetes has been modified throughout the years and that many of these participants underwent testing prior to or during these changes, the accuracy of some of the diabetes diagnoses in this cohort could be called into question. In addition, the researchers were unable to provide evidence that the study findings could be generalized to nonwhite and female patients.
The investigators suggest that cardiovascular complications that correlated with the elevated glucose readings at 1 hour in this study were primarily associated with “body composition, cholesterol levels, and subclinical target organ damage, including arterial stiffness, carotid intima-media thickness, and left ventricular hypertrophy.”
Pareek M, Bhatt DL, Nielsen ML, et al. Enhanced predictive capability of a 1-hour oral glucose tolerance test: a prospective population-based cohort study [published online November 14, 2017]. Diabetes Care. doi:10.2337/dc17-1351