Association between surrogate indicators of insulin resistance and risk of type 2 diabetes combined with hypertension among Chinese adults: two independent cohort studies

Abstract

Background: Type 2 diabetes (T2D) combined with hypertension has a higher risk of developing cardiovascular diseases. This study aimed to investigate the relationships between the surrogate indicators of insulin resistance (TyG, TG/HDL, and Mets-IR) with the risk of T2D combined with hypertension. Methods: This study is based on a functional community cohort from Beijing and the China Health and Retirement Longitudinal Study, comprising 4234 and 4658 participants respectively. Cox proportional hazards models and restricted cubic spline regression were performed to assess the link between TyG, TG/HDL, and Mets-IR with T2D combined with hypertension. The cross-lagged panel analysis and the mediation analysis were used to examine the temporal relationship between insulin resistance and obesity and their temporal relationship with follow-up T2D combined with hypertension. Results: In multivariable-adjusted models, higher TyG was associated with a higher risk of developing T2D combined with hypertension, the hazard ratios (95% confidence interval) were 3.46 (2.43–4.93) and 2.02 (1.67–2.44), in two cohorts respectively. A similar positive association was shown for Mets-IR, the hazard ratios (95% confidence interval) were 1.04 (1.03–1.06) and 1.05 (1.03–1.07), in two cohorts respectively. However, the association between TG/HDL with T2D combined with hypertension was different in two cohorts. The restricted cubic spline regression showed a linear association between TyG and T2D combined with hypertension (P-nonlinear > 0.05). The cross-lagged path coefficient from baseline BMI to follow-up TyG index was significantly greater than the path coefficient from baseline TyG to follow-up BMI. TyG partially mediated the effect of BMI on the risk of T2D combined with hypertension and the percentage of mediated association was estimated at 41.58% and 48.41% in two cohorts, respectively. Conclusion: These findings indicated positive associations between TyG and Mets-IR with the risk of T2D combined with hypertension in two cohorts. In addition, BMI change may precede TyG index change, and the TyG index plays a mediating role in BMI induced T2D combined with hypertension.