Association Between the Triglyceride–Glucose Index and Glycated Hemoglobin (HbA1c) in Patients with Type 2 Diabetes Mellitus at Sisaket Hospital

Abstract

              This study aimed to examine the association between the triglyceride–glucose (TyG) index and glycated hemoglobin (HbA1c) and to assess the ability of the TyG index to discriminate between patients with type 2 diabetes mellitus with HbA1c ≥7% and those with HbA1c <7%. This analytical cross-sectional study used retrospective data from Sisaket Hospital between October 1, 2024, and September 30, 2025. The sample comprised 519 patients, with one examination record per patient. The TyG index was calculated from fasting triglyceride and glucose levels. Data were analyzed using descriptive statistics, Spearman’s rank correlation, multiple linear regression adjusted for age, sex, and body mass index, and receiver operating characteristic (ROC) curve analysis. The optimal cutoff was selected by maximizing the Youden index.

            Of the participants, 57.03% were female, and the mean age was 59.40±11.85 years. The mean TyG index was 9.14±0.65, and the median HbA1c was 7.40% (interquartile range: 6.50–8.90%). Overall, 61.27% had HbA1c ≥7%. The TyG index was positively correlated with HbA1c (rₛ=0.470; 95% CI: 0.392–0.540; p<0.001). This association remained significant after adjustment for covariates (B=1.687; 95% CI: 1.336–2.039; p<0.001), with an R² of 0.235. The area under the ROC curve was 0.695 (95% CI: 0.650–0.741). A TyG index cutoff of ≥9.2223 yielded a sensitivity of 52.83%, specificity of 80.10%, positive predictive value of 80.77%, and negative predictive value of 51.77%. The TyG index was positively associated with HbA1c after adjustment for age, sex, and body mass index. However, its sensitivity for identifying patients with HbA1c ≥7% was limited. It may provide supplementary information for patient assessment alongside HbA1c and clinical data.