Sex-stratified associations of TyG index and HOMA-IR changes with incident type 2 diabetes

Early identification of individuals at risk of type 2 diabetes is important in young and middle-aged adults. Although the homeostatic model assessment of insulin resistance (HOMA-IR) is widely used, its limited clinical practicality has increased interest in the triglyceride-glucose (TyG) index as a simpler surrogate marker of insulin resistance. However, the predictive values of longitudinal changes in these indices remain unclear. We analyzed data from 271,592 Korean adults aged 18-49 years who underwent at least two health screening examinations. Changes in the TyG index and HOMA-IR were categorized into sex-specific quintiles. Incident type 2 diabetes was defined as fasting glucose ≥ 126 mg/dL, HbA1c ≥ 6.5%, or initiation of antidiabetic medication. Hazard ratios were estimated using the Cox proportional hazard models. During the follow-up period, 3,841 men and 1,069 women developed type 2 diabetes. Greater increases in the TyG index were consistently associated with a higher risk of diabetes across quintiles in both sexes. The associations with HOMA-IR changes were more variable across analytical models, particularly in the lower quintiles. These findings suggest that monitoring changes in both indices may provide additional information for diabetes risk assessment, with the TyG index showing more consistent associations across models in our study. Further studies in diverse populations are needed to confirm these observations.