Aim: To evaluate the diagnostic performance of the Triglyceride Glucose (TyG) index in predicting prediabetes and to assess its utility as a practical screening tool in primary healthcare settings. Material and Methods: This retrospective case control study included 350 adults with prediabetes and 350 age and sex matched normoglycemic controls from a Family Medicine Unit in Izmir, Türkiye. Data on sociodemographic characteristics, lifestyle factors, anthropometric measurements, and laboratory values were obtained from electronic medical records. ROC curve analysis and three step logistic regression models were used to determine the predictive value of the TyG index and its association with prediabetes risk. Results: The TyG index was significantly higher in the prediabetes group than in controls (p < 0.001). Logistic regression showed that each one-unit increase in the TyG index was associated with a 2.26 fold increase in prediabetes risk. Individuals in the highest TyG quartile had a 3.71–4.20 fold increased risk compared to the lowest quartile across models. The TyG index also showed strong correlations with HbA1c, fasting glucose, lipid parameters, and waist circumference. ROC analysis yielded an AUC of 0.680 for the TyG index alone, which increased to 0.834 when combined with fasting glucose and lifestyle variables. Conclusion: The TyG index is a low cost, accessible, and effective screening marker for prediabetes in primary care. Its integration into clinical decision making processes may support early identification and risk stratification of individuals prone to developing type 2 diabetes.