Association between triglyceride glucose index and carotid intima-media thickness in obese and nonobese adults

Background The triglyceride glucose (TyG) index is closely associated with subclinical atherosclerosis. However, the association remains inconclusive among obese and nonobese individuals. Methods This prospective study was conducted in 5751 adults with normal carotid intima-media thickness (CIMT) at baseline. We divided the population into four groups based on the TyG index, which was calculated by the following formula: Ln (fasting triglycerides [mg/dL] x fasting glucose [mg/dL]/2). Information on CIMT was acquired by ultrasonography. Incident elevated CIMT was defined as IMT values greater than 0.9 mm at follow-up. Odds ratios (ORs) and 95% confidence intervals (CIs) of the associations between TyG index and elevated CIMT were estimated using multivariable logistic regression models. Results After a median follow-up of 4.3 years, 722 (12.6%) individuals had progressed to elevated CIMT. Compared with the second quartile of the TyG index, the first and fourth quartile both conferred higher risks of elevated CIMT after adjusting for potential confounders. In the total population, the ORs for the first and fourth quartile were 1.29 (95% CI, 1.00-1.66) and 1.42 (95% CI, 1.11-1.83), respectively. Restricted cubic splines demonstrated an approximately U-shaped association between TyG index and elevated CIMT among the total and nonobese adults (P for nonlinearity <.05), but not in those with general or abdominal obesity. Conclusions A U-shaped association was observed between TyG index and elevated CIMT only among nonobese Chinese adults.