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1-Hour Post-Prandial Glucose Predicts Risk For Type 2 Diabetes

Study finds diabetes complications and mortality may be better predicted with elevated 1-hour blood glucose levels compared with 2-hour blood glucose levels.

Michael Bergman, MD, FACP, clinical professor of medicine at NYU School of Medicine, director of the NYU Diabetes Prevention Program and co-author of this study wrote in an article that, “A 1-hour blood glucose measurement during an oral glucose tolerance test appears to be a significant predictor for the development of type 2 diabetes….The measurement is also more sensitive than the 2-hour value for identifying high-risk individuals and can predict as well as the risk for diabetes complications and mortality. Therefore, the 1-hour test could replace the traditional 2-hour test, making it more acceptable in clinical practice.”

To examine whether the 1-h blood glucose measurement would be a more suitable screening tool for assessing the risk of diabetes and its complications than the 2-h measurement, a prospective population-based cohort study of 4,867 men, randomly selected from birth cohorts between 1921 and 1949, who underwent an oral glucose tolerance test with blood glucose measurements at 0, 1, and 2 hours was done. Subjects were followed for up to 39 years. Discriminative abilities of elevated 1-h at 155 mg/dL. (+8.6mmol/L) versus 2-h at 140 mg/dL. (+7.8mmol/L) glucose for predicting incident type 2 diabetes, vascular complications, and mortality were compared.

The median age was 48 years. During follow-up (median 33 years), 636 (13%) developed type 2 diabetes. Elevated 1-h glucose was associated with incident diabetes and provided better risk assessment than impaired glucose tolerance. The addition of a 1-h measurement in subjects stratified by fasting glucose provided greater net reclassification improvement than the addition of a 2-h measurement. Finally, the 1-h glucose was significantly associated with vascular complications and mortality.

From the results, the 1-h blood glucose level was a stronger predictor of future type 2 diabetes than the 2-h level and is associated with diabetes complications and mortality. Plus, several randomized clinical trials provide evidence that type 2 diabetes can be prevented or at least postponed with lifestyle modification and drug therapy, which makes identifying high-risk individuals particularly important. Traditionally, prediabetes has been defined as impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) during a 2-h oral glucose tolerance test (OGTT), and interventional studies thus far have predominantly included subjects with IGT. However, not all subjects with prediabetes develop type 2 diabetes, and conversely, a considerable number without prediabetes progress to type 2 diabetes. Accumulating longitudinal evidence, Abdul-Ghani et al. suggests that the 1-h post-load glucose level during OGTT with a cutoff 155 mg/dl. (8.6 mmol/L) may be an early marker of IGT and subsequent type 2 diabetes that is potentially more useful than either fasting or 2-h glucose levels. Furthermore, from a pathophysiological perspective, the 1-h glucose level is intriguing owing to its seemingly strong correlation with markers of both insulin secretion and sensitivity.  However, practical clinical implications of using a 1-h glucose measurement for prediction of type 2 diabetes and its associated complications are less clear. Therefore, the aim of this study was to examine whether the 1-h blood glucose measurement would be a more suitable screening tool for risk assessment than the 2-h blood glucose alone.

In conclusion, the results demonstrate that in middle-aged men, for whom screening for type 2 diabetes would be recommended, the 1-h blood glucose level is a significant predictor of future type 2 diabetes, regardless of the 2-h blood glucose level. In addition, the 1-h blood glucose level has greater detection rates (higher sensitivity) than the 2-h blood glucose level and can correctly reclassify subjects with traditionally defined prediabetes, especially with longer duration of follow-up (high specificity). Importantly, the 1-h blood glucose level is also associated with diabetes complications, including risks for mortality, myocardial infarction, fatal ischemic heart disease, retinopathy and peripheral vascular complications were greater in participants with elevated 1-hour blood glucose levels than those with elevated 2-hour blood glucose levels.

Given the results of this study, it seems possible that targeting subjects with an abnormal 1-hour blood glucose level could halt the progression to manifest diabetes in an even larger number of individuals. Thus, the most desirable next step would be a randomized study of intensive lifestyle therapy vs. control in patients enrolled based on an abnormal 1-hour blood glucose level.

Practice Pearls:

  • From the results of the study, the 1-h blood glucose level was a stronger predictor of future type 2 diabetes than the 2-h glucose level
  • An elevated 1-h blood glucose level is also associated with diabetes complications including risks for mortality, myocardial infarction, fatal ischemic heart disease, retinopathy and peripheral vascular complications.
  • Targeting subjects with an abnormal 1-hour blood glucose level could halt the progression to manifest diabetes in an even larger number of individuals, then the fasting blood glucose result.

References:

Enhanced Predictive Capability of a 1-Hour Oral Glucose Tolerance Test: A Prospective Population-Based Cohort Study; Manan Pareek, Deepak L. Bhatt, Mette L. Nielsen, Ram Jagannathan, Karl-Fredrik Eriksson, Peter M. Nilsson, Michael Bergman and Michael H. Olsen Diabetes Care 2017 Oct; dc171351. https://doi.org/10.2337/dc17-1351

Abdul-Ghani MA, Williams K, DeFronzo RA, Stern M. What is the best predictor of future type 2 diabetes? Diabetes Care 2007;30:1544–1548Marini MA, Succurro E, Frontoni S, et al. Insulin sensitivity, b-cell function, and incretin effect in individuals with elevated 1-hour postload plasma glucose levels. Diabetes Care 2012;35:868–872 20.

Bianchi C, Miccoli R, Trombetta M, et al.; GENFIEV Investigators. Elevated 1-hour postload plasma glucose levels identify subjects with normal glucose tolerance but impaired b-cell function, insulin resistance, and worse cardiovascular risk profile: the GENFIEV study. J Clin Endocrinol Metab 2013;98:2100–2105  Healio ITJ Journal Nov.14, 2017