This retrospective study investigated the risk of primary open-angle glaucoma (POAG) among individuals identified as glaucoma suspects and examined associated cardiovascular risk factors. We conducted a longitudinal, nationwide cohort study using data from the Korean National Health Insurance Service (KNHIS) and included 362,285 participants aged ≥ 40 years from the Korean National Health Screening Program (NHSP) without pre-existing POAG in 2009 and 2010. Of these, glaucoma suspects (n = 32,220) were defined as individuals with at least two recorded instances of the KCD code H400 for glaucoma suspect and no prior antiglaucoma medication prescriptions before health screening. The primary outcome was the diagnosis of POAG and the prescription of antiglaucoma medications. Over a 6-year follow-up, 4.92% of glaucoma suspects developed POAG. Through multivariate Cox regression analysis, glaucoma suspects with diabetes, hypertension, dyslipidemia, or coronary heart disease exhibited a greater risk of conversion to POAG than those without these comorbidities ([HR, 1.354; 95%CI, 1.201 to 1.527] for diabetes, [HR, 1.139; 95%CI, 1.019 to 1.273] for systemic hypertension, [HR, 1.128; 95%CI, 1.013 to 1.26] for dyslipidemia, [HR, 1.124, 95%CI, 1.007 to 1.254] for coronary heart disease).This nationwide study observed that among glaucoma suspects, having cardiovascular risk factors/disease was associated with higher risk of developing POAG.