Nonlinear Relationship Between the Triglyceride–Glucose Index and All‐Cause and Cardiovascular Mortality in Diabetes Mellitus Patients With Hypertension: A National Cohort Study

Background The impact of the triglyceride–glucose (TyG) index on mortality in diabetes patients with hypertension remains unclear. Methods This retrospective cohort study included 3296 participants from the National Health and Nutrition Examination Survey (2001–2018). The TyG index was calculated as Ln [fasting triglycerides (mg/dL) × fasting glucose (mg/dL)/2]. Multivariable Cox proportional hazards models adjusted for demographic and clinical confounders were used to estimate mortality risks. Restricted cubic spline analysis assessed nonlinear relationships between TyG index and mortality risk. Stratified analyses and interaction tests were conducted based on gender, age, race, body mass index, smoking status, and the presence of cardiovascular disease. Results A total of 3296 individuals were ultimately included in the study cohort. Over a median follow‐up of 82 months (IQR, 44–129), 912 participants (27.7%) died, with 315 (9.6%) from cardiovascular disease. A nonlinear association between TyG index and mortality was observed, with inflection points at 8.9 for all‐cause mortality and 9.0 for cardiovascular mortality. Hazard ratios (95% CI) were 0.85 (0.62–1.16) and 1.38 (1.14–1.67) for all‐cause mortality and 0.70 (0.44–1.01) and 1.78 (1.27–2.48) for cardiovascular mortality, below and above these points, respectively. In participants aged < 65 years, elevated TyG index levels showed significantly greater susceptibility to all‐cause mortality [HR = 1.69 (1.20–2.39), p < 0.003, interaction p = 0.01]. Conclusion In this national cohort of adults with diabetes and hypertension, the TyG index showed a nonlinear association with mortality: the risk of all‐cause death increased above TyG = 8.9 and cardiovascular death above TyG = 9.0; associations were stronger among participants under 65 years old.