AimThis study aimed to examine whether cumulative exposure to hypertriglyceridemia is associated with an increased risk of developing type 2 diabetes in young adults. MethodsThe study included 1,840,251 participants aged 20–39 years who had undergonefourconsecutiveannualhealth checkups and had no history of type 2 diabetes. Participants werecategorized into five groups (exposure score 0–4) based on the frequencies of hypertriglyceridemia diagnosis over a four-year period. The primary outcome was newly diagnosed type 2 diabetes. Exploratory analyses were performed for the different subgroups. ResultsDuring a follow-up period of 6.53 years, 40,286 participants developed type 2 diabetes. The cumulative incidence of type 2 diabetes significantly increased with higher exposure scores for hypertriglyceridemia (log-rank test, P < 0.001). The multivariable-adjusted hazard ratios for incident diabetes were 1.674 (95 % CI, 1.619, 1.732), 2.192 (95 % CI, 2.117, 2.269), 2.637 (95 % CI, 2.548, 2.73), and 3.715 (95 % CI, 3.6, 3.834) for participants with scores of 1–4, respectively, compared with those with an exposure score of 0. ConclusionsIn this large-scale prospective cohort study of young adults, cumulative exposure to hypertriglyceridemia was significantly associated with an increased risk of type 2 diabetes, independent of lifestyle-related factors.