ObjectiveTo investigate the association between the cholesterol, high-density lipoprotein, and glucose (CHG) index and type 2 diabetes mellitus prevalence in US adults.MethodsThis cross-sectional study included 11,390 participants from the National Health and Nutrition Examination Survey 2009-2018 cycles. The CHG index was calculated using total cholesterol, high-density lipoprotein, and fasting blood glucose levels. Weighted logistic regression was used to assess the association between the CHG index and type 2 diabetes mellitus prevalence, and restricted cubic spline analysis was applied to examine potential nonlinear relationships. Receiver operating characteristic curves were used to evaluate the diagnostic performance of the CHG index, and the results were compared with those of the triglyceride-glucose index.ResultsA higher CHG index was significantly associated with increased type 2 diabetes mellitus prevalence (odds ratio: 4.30, 95% confidence interval: 3.21-5.77, p < 0.001) after adjusting for multiple confounders. Restricted cubic spline analysis showed a nonlinear relationship, demonstrating an elevated risk of type 2 diabetes mellitus in patients with a CHG index of >5.24. The association remained consistent across all subgroups. The CHG index demonstrated good predictive value (area under the curve = 0.721; optimal cutoff = 5.47; sensitivity = 0.53; specificity = 0.80), comparable to that of the triglyceride-glucose index (area under the curve = 0.730; optimal cutoff = 8.84; sensitivity = 0.62; specificity = 0.73).ConclusionThe CHG index may be associated with type 2 diabetes mellitus prevalence and could serve as a simple, accessible biomarker for early risk identification. Further prospective studies are needed to validate its clinical utility.