Do We Need the Oral Glucose Tolerance Test to Identify Future Cases of Type 2 Diabetes?

In our recent article (1), in which we presented a predicting model based on readily available clinical variables for identifying individuals at high risk of future type 2 diabetes, we concluded with the words: “… we hope that this report will stimulate other researchers with suitable databases to evaluate (similar) prediction models… ” The first group to take up this challenge is McNeely et al. (2), whose report appears in this issue of Diabetes Care . The results of their analyses in Japanese Americans raise the interesting possibility that the predicting model performs better in younger than older individuals.A major difference between the Japanese-American cohort and our San Antonio cohort was the older age range of the former (34–75 years, mean ∼52 vs. 25–64, mean 43.5). One reason why 2-h glucose might play a larger role in predicting future diabetes in older subjects is that the other risk factors for diabetes, notably, lipids and blood pressure, are also risk factors for cardiovascular disease. Thus, the older the cohort, the greater the likelihood that individuals with risk factors will fail to return for follow-up glucose tolerance testing as a result of having developed either cardiovascular morbidity or mortality. It thus becomes less likely that these same risk factors will emerge as predictive of diabetes. The finding by McNeely et al. that BMI is a stronger risk factor in individuals <55 years of age supports this concept. Based on their suggestion, we have reanalyzed our data and have also observed an interaction in the same direction between age and BMI. McNeely et al. also observed an interaction between age and HDL, although we did not.All of the above points notwithstanding, however, it must be acknowledged that the fact that only eight individuals in the study by McNeely et al. died …