Combination of triglyceride-glucose index and waist-to-height ratio as a predictor of all-cause and cardiovascular mortality in adults with diabetes or prediabetes: a nationwide prospective cohort study

Background: Insulin resistance (IR) and central obesity play a crucial role in the pathogenesis of metabolic diseases. However, the association between the triglyceride-glucose index combined with waist-to-height ratio (TyG-WHtR)—a novel proxy for both insulin resistance and central obesity—and mortality outcomes in adults with prediabetes and diabetes remains unclear. The aim of this study is to explore the association between TyG-WHtR and all-cause and cardiovascular (CVD) mortality in prediabetic and diabetic adults. Methods: The study enrolled 19,563 United States (U.S.) adults diagnosed with prediabetes or diabetes from the National Health and Nutrition Examination Survey (NHANES). Data were collected in eight continuous 2-year cycles from January 2003 to December 2018. The Kaplan-Meier curve, Cox proportional risk model, restricted cubic spline (RCS) curve, and subgroup analysis were used to evaluate the association of the TyG-WHtR index with all-cause mortality and CVD-related mortality in US adults with prediabetes and diabetes. A series of sensitivity analyses were performed to test the robustness of the findings. Results: After a median follow-up of 7.6 years, 2,949 all-cause deaths were recorded (15.1% death rate over the follow-up period), of which 969 (32.86%) were CVD related. Multivariate adjustment models showed a gradual increase in all-cause mortality and CVD-related mortality with each increasing TyG-WHtR index quartile. Specifically, for every one unit increase in TyG-WHtR, the risk of all-cause death increased by 19% [hazard ratio (HR) =1.19, 95% confidence interval (CI): 1.1–1.28; P<0.001] and there was also an associated 11% increased risk of death from CVD, although this did not reach statistical significance (HR =1.11, 95% CI: 0.98–1.27; P=0.11). Compared with patients in the lowest quartile (Q1), those in the highest quartile (Q4) had an all-cause mortality HR of 1.39 (95% CI: 1.06–1.81) and a CVD-related mortality HR of 1.36 (95% CI: 0.91–2.03). Interaction tests revealed significant effect modification by body mass index (BMI) (all-cause mortality) and family income-to-poverty ratio (CVD-related mortality). Conclusions: In a sample of US adults with prediabetes and diabetes, we found an association between TyG-WHtR index and both all-case and CVD-related mortality. The TyG-WHtR index could serve as an alternative biomarker for the clinical management of patients with prediabetes and diabetes.