Triglyceride-Glucose (TyG) Index and Its Association with Vitamin D Status and Cardiovascular Risk Factors in Patients with Type 2 Diabetes Mellitus
Introduction: Insulin resistance, dyslipidemia, and increased risk of developing cardiovascular diseases have been identified in patients with type 2 diabetes mellitus (T2DM). Triglyceride – Glucose (TyG) index has been identified as the surrogate marker for insulin resistance and vitamin D deficiency is known to contribute to poor metabolic profile. This study aimed at exploring the relation between TyG index and vitamin D and their association with cardiovascular disease risk factors in patients with T2DM. Materials and Methods: Hospital-based cross-sectional study was carried out on 156 patients with T2DM presenting in tertiary care hospital. Anthropometry, fasting blood glucose, HbA1c, lipid profile, and serum vitamin D were determined. TyG index, Cardiac Risk Ratio (CRR), Atherogenic Coefficient (AC) and Atherogenic Index of Plasma (AIP) were calculated. Group comparisons based on vitamin D deficiency and correlations were carried out using one-way ANOVA, Chi square and Spearman’s rank correlation. Results: The mean age of participants was 52.1 ± 10.4 years, mean BMI was 27.3 ± 3.2 kg/m², mean TyG index was 9.85 ± 0.24, and mean serum vitamin D concentration was 18.0 ± 7.3 ng/mL. Vitamin D deficiency was observed in 94 (60.3%) participants. Patients with vitamin D deficiency had higher BMI (28.6 ± 4.3 vs. 25.1 ± 3.2 kg/m²), TyG index (10.01 ± 0.25 vs. 9.63 ± 0.21), HbA1c (8.1 ± 1.6% vs. 7.5 ± 1.3%), Cardiac Risk Ratio (5.4 ± 1.7 vs. 4.5 ± 1.3), and Atherogenic Index of Plasma (0.32 ± 0.26 vs. 0.18 ± 0.20) than vitamin D-sufficient participants. One-way ANOVA demonstrated significant differences in BMI (F (2,153) = 7.58, p < 0.001), TyG index (F (2,153) = 13.42, p < 0.001), Cardiac Risk Ratio (F (2,153) = 3.40, p = 0.036), and Atherogenic Index of Plasma (F (2,153) = 3.27, p = 0.040), whereas differences in HbA1c were not statistically significant (F (2,153) = 1.55, p = 0.216). Vitamin D status showed significant associations with gender (χ² = 10.03, df = 2, p = 0.007) and BMI category (χ² = 15.44, df = 4, p = 0.004), whereas no significant association was observed with age group (χ² = 1.23, df = 4, p = 0.873). Spearman correlation analysis demonstrated that the TyG index was positively correlated with HbA1c (ρ = 0.46), Cardiac Risk Ratio (ρ = 0.52), and Atherogenic Index of Plasma (ρ = 0.61), and negatively correlated with vitamin D (ρ = −0.41) (all p < 0.001). Conclusions: The TyG index was significantly associated with adverse glycemic and atherogenic markers and inversely associated with vitamin D levels in patients with type 2 diabetes mellitus. These findings suggest that the TyG index and vitamin D status are associated with cardiometabolic risk factors; however, the cross-sectional design precludes causal inference, and prospective studies are needed to confirm these associations. Key words: TyG index, Vitamin D, Insulin resistance, Type 2 diabetes mellitus, Cardiovascular risk