Temporal relationship between triglyceride-glucose index and blood pressure and their joint cumulative effect on cardiovascular disease risk: a longitudinal cohort study

Background Concurrent insulin resistance and elevated blood pressure are commonly observed in cardiovascular disease (CVD) and have long been proposed to contribute to CVD. However, the temporal relationship between them and the effect of their cumulative co-exposure on future incident CVD remains unclear.Methods Longitudinal analysis of data on 57,192 participants from a real-world, prospective cohort study (Kailuan Study) was performed to address the temporal relationship between Triglyceride-Glucose Index (TyG, calculated as ln [TG (mg/dL) x FBG (mg/dL)/2]) and blood pressure (BP) assessed by cross-lagged analyses in an approximately 4-year exposure period (2006/2007 to 2010/2011). After excluding 879 participants with known diabetes, 56,313 nonCVD participants were included for further analysis of the CVD outcome. Cox regression models were used to examine the hazard ratios (HRs) upon the cumulative TyG (CumTyG) and BP(CumBP) in the exposure period.Results The standard regression coefficient from baseline TyG to follow-up systolic BP was 0.0142 (95% CI 0.0059-0.0226), which was greater than the standard regression coefficient from baseline systolic BP to follow-up TyG (- 0.0390; 95% CI - 0.0469 to - 0.0311). The same results were observed in the cross-lag between TyG and diastolic blood pressure [0.0271 (0.0185 to 0.0356) vs. - 0.0372 (- 0.0451 to - 0.0293)]. During a median follow-up of 9.98 years, 3981 CVD cases occurred. Significant interactions were observed between the median CumTyG (8.61) and CumSBP thresholds (130, 140 mmHg) (P = 0.0149), the median CumTyG (8.61) and CumDBP thresholds (80, 90 mmHg) (P = 0.0441). Compared to CumTyG < 8.61 and CumSBP < 130 mmHg, after adjusting for potential confounding factors, the HR gradually increased in the high co-exposure groups. The hazard ratios (HRs) and 95% confidence intervals (CIs) for Q2-Q6 were 1.39 (1.24, 1.57), 1.94 (1.69, 2.22), 2.40 (2.12, 2.71), 2.74 (2.43, 3.10), and 3.07 (2.74, 3.45). Additionally, the CVD risks in the co-exposure were more prominent in younger participants.Conclusions These findings suggest that elevated TyG has a greater impact on future blood pressure changes than vice versa. Dual assessment and management of insulin resistance and blood pressure contribute to the prevention of CVD, especially in younger individuals.