A new article published in the American Journal of Epidemiology reported that type-1 diabetes (T1D) is associated with increased cardiovascular disease (CVD) risk, but hyperglycemia, measured by HbA1c (%) – which characterizes T1D, has itself been an inconsistent CVD predictor. This article elaborated on data from the Pittsburgh Epidemiology of Diabetes Complications (EDC) study – an ongoing, prospective cohort study of childhood-onset T1D, which reported little association between baseline or mean follow-up HbA1c and coronary artery disease incidence. The results had showed that of the 561 participants without CVD at baseline, 263 developed CVD over 25 years. On the other hand, each one percent increase in HbA1c trajectory was associated with a 1.3-fold rise in CVD risk after adjusting for baseline values of other CVD risk factors, and a 1.13-fold increase in CVD risk after adjusting for updated means of other CVD factors. In summary, it was stated that these findings support the need for good glycemic control to prevent CVD in T1D, as well as highlight the importance of utilizing methods incorporating subjective variation over time when analyzing and interpreting longitudinal cohort study data.