ABSTRACTBackgroundDespite previous studies, the relationship between the triglyceride‐glucose (TyG) index and coronary artery disease (CAD) is still undetermined. So we aimed to investigate the association between the TyG index and CAD.MethodA total of 2346 subjects were enrolled in the study and were categorised into 5: those with no CAD, angiogram negative (Ang−) patients, those with single‐vessel disease (SVD), or two‐vessel disease (2VD) or three‐vessel disease (3VD). Demographic characteristics, disease history and biochemical investigations were recorded. TyG index was calculated as Ln [fasting TG (mg/dL) × fasting glucose (mg/dL)/2].ResultsAdjusted regression models demonstrated that the odds of 3VD (OR, 5.847; 95% CI, 4.391–7.784), 2VD (OR, 4.943; 95% CI, 3.597–6.791), SVD (OR, 4.722; 95% CI 3.448–6.647) and a negative coronary angiogram (OR, 3.137; 95% CI, 2.431–4.049), increased significantly per each unit elevation of the TyG index, compared to the healthy participants. Also, the odds for being 3VD (1.864, 95%CI 1.402–2.477, p‐value < 0.001), 2VD (1.575, 95%CI 1.143–2.171, p‐value = 0.005) and SVD (1.505, 95%CI 1.097–2.065, p‐value = 0.011) were increased significantly by one‐unit elevation of TyG index, compared to Ang− group.ConclusionOur study demonstrates a significant association between elevated TyG index and the presence and severity of CAD. Higher TyG index values were consistently linked to an increased likelihood of multivessel CAD, especially in diabetic patients. These findings suggest that the TyG index could serve as a valuable marker for assessing CAD risk and stratification.