Evaluation of HbA1c trend analysis as a Prognostic Tool in type 2 diabetes mellitus

Background: Glycated haemoglobin (HbA1c) is the standard measure of glycaemic control in type 2 diabetes mellitus (T2DM), and landmark trials linked sustained elevation to microvascular and macrovascular risk [2,3]. The longitudinal trend and visit-to-visit variability of HbA1c are increasingly examined as independent prognostic signals. Objective: This review evaluates HbA1c trend and variability analysis as a prognostic tool for mortality and vascular complications in T2DM, compared with single-timepoint HbA1c and continuous glucose monitoring (CGM) metrics. Methods: We synthesized major randomized trials, prospective and retrospective cohorts, and registry analyses addressing HbA1c trajectory, variability, and outcomes in adults with T2DM. Findings: Higher HbA1c variability independently predicts all-cause mortality and cardiovascular events after adjustment for mean HbA1c [10,11,12], with hazard ratios of 1.5-2.5 for highest versus lowest variability strata. Registry data show a U-shaped mean HbA1c-mortality association, with risk rising at both extremes [16]. CGM-derived metrics complement but do not replace HbA1c trend analysis [26,27]. Conclusions: HbA1c trend and variability analysis adds independent prognostic information beyond a single measurement and should inform risk stratification in T2DM [17,13].