Normal triglyceride levels are positively associated with plasma glucose levels and type 2 diabetes diagnosis in Chinese adults

Aim: Hypertriglyceridemia is linked to increased risk of diabetes diagnosis, incidence, and mortality. However, whether individuals with normal triglyceride levels (i.e., < 1.7 mmol/L) uniformly exhibit low diabetes risk remains underexplored. Specifically, it is unclear whether triglyceride levels within the normal range are associated with plasma glucose levels and the prevalence of type 2 diabetes (T2DM). This study aimed to address these gaps by examining the associations between triglyceride levels and fasting plasma glucose, as well as between triglyceride levels and T2DM, in individuals with triglycerides in the normal range. Methods: This cross-sectional study included 16,706 Chinese adults with triglyceride levels below 1.7 mmol/L. Among them, 1,067 had T2DM. Associations between triglyceride levels and fasting plasma glucose were assessed using linear regression, while associations with T2DM were evaluated using binary logistic regression. The optimal triglyceride cut-off for T2DM diagnosis was determined via receiver operating characteristic (ROC) curve analysis. Results: Triglyceride levels were positively associated with fasting plasma glucose after multivariate adjustment (β = 0.034, P < 0.001). A one-unit increase in the natural log of triglyceride levels was associated with a 61% higher adjusted odds of T2DM [odds ratio (OR), 1.61; 95% confidence interval (CI), 1.19–2.17; P = 0.002]. The optimal triglyceride cut-off for T2DM diagnosis was 1.09 mmol/L. Participants with triglyceride levels ≥ 1.09 mmol/L had a 28% higher odds of T2DM (OR, 1.28; 95% CI, 1.07–1.53; P = 0.006) compared to those with levels below the cut-off. Conclusions: Among individuals with normal triglyceride levels, higher triglyceride concentrations were associated with higher odds of T2DM diagnosis, with an optimal diagnostic cut-off of 1.09 mmol/L. These findings suggest that adults with triglyceride levels more than 1.09 mmol/L may benefit from closer monitoring for T2DM development.