Prediabetes is an intermediate state of hyperglycemia between normoglycemia and diabetes mellitus (DM), with a larger population affected compared to patients with diabetes and a higher incidence of cardiovascular events. Prediabetes is associated with an increased risk of cardiovascular disease (CVD); however, the long-term benefits of intervening in prediabetes on microvascular and macrovascular outcomes remain controversial. Glycated hemoglobin (HbA1c) serves as not only a diagnostic indicator of abnormal glucose metabolism, but also a fundamental biomarker for continuous glucose monitoring, with its elevated levels closely related to cardiovascular diseases. This article reviews the association between HbA1c, prediabetes, and CVD, aiming to elucidate the utility of HbA1c as a composite indicator for assessing cardiovascular risk in non-diabetic populations. Furthermore, HbA1c below the threshold for diabetes can stratify cardiovascular risk, thereby offering valuable information for current and future strategies in the prevention of CVD.