Limited research has explored the effectiveness of insulin resistance (IR) in forecasting metabolic syndrome (MetS) risk, especially within the Iranian population afflicted with type 2 diabetes mellitus (T2DM). The present investigation aimed to assess the efficacy of IR indices in predicting the risk of MetS among T2DM patients. Convenient sampling was utilized to select four hundred subjects with T2DM. Metabolic factors and IR indices, including the Waist Circumference-Triglyceride Index (WTI), Triglyceride and Glucose Index (TyG index), the product of TyG index and abdominal obesity indices, and the Metabolic Score for Insulin Resistance (METS-IR), were evaluated. Logistic regression, coupled with modeling, was employed to explore the risk of MetS. The predictive performance of the indices for MetS stratified by sex was evaluated via receiver operating characteristic (ROC) curve analysis and estimation of the area under the curve (AUC) values. The TyG-Waist Circumference (TyG-WC) index exhibited the largest AUCs in both males (0.91) and females (0.93), while the TyG-Body Mass Index (TyG-BMI) demonstrated the smallest AUCs (0.77 in males and 0.74 in females). All indices significantly predicted the risk of MetS in all subjects before and after adjustment (p < 0.001 for all). The TyG-WC index demonstrated the highest odds ratios for MetS (8.06, 95% CI 5.41–12.00). In conclusion, all IR indices assessed in this study effectively predicted the risk of MetS among Iranian patients with T2DM, with the TyG-WC index emerging as the most robust predictor across both genders.

Background: Vitamin D supplementation exerts several supporting effects on improving glycemic status, however, results are inconclusive. Thus, in the present study, we aimed to conduct an umbrella of meta-analysis regarding the impact of vitamin D on type 2 diabetes (T2DM) biomarkers. Methods: The Scopus, PubMed, Web of Science, Embase, and Google Scholar online databases were searched up to March 2022. All meta-analyses evaluating the impact of vitamin D supplementation on T2DM biomarkers were considered eligible. Overall, 37 meta-analyses were included in this umbrella meta-analysis. Results: Our findings indicated that vitamin D supplementation significantly decreased fasting blood sugar (FBS) (WMD = − 3.08; 95% CI: − 3.97, − 2.19, p < 0.001, and SMD = − 0.26; 95% CI: − 0.38, − 0.14, p < 0.001), hemoglobin A1c (HbA1c) (WMD = − 0.05; 95% CI: − 0.10, − 0.01, p = 0.016, and SMD = − 0.16; 95% CI: − 0.27, − 0.05, p = 0.004), insulin concentrations (WMD = − 2.62; 95% CI: − 4.11, − 1.13; p < 0.001, and SMD = − 0.33; 95% CI: − 0.56, − 0.11, p = 0.004), and homeostatic model assessment for insulin resistance (HOMA-IR) (WMD = − 0.67; 95% CI: − 1.01, − 0.32, p < 0.001, and SMD = − 0.31; 95% CI: − 0.46, − 0.16, p < 0.001). Conclusion: This umbrella meta-analysis proposed that vitamin D supplementation may improve T2DM biomarkers.

Several meta-analyses have revealed that n-3 PUFAs can lower blood pressure, but the findings are conflicting. In this regard, the present umbrella meta-analysis aimed was performed to clarify whether n-3 PUFAs have effects on blood pressure. PubMed, Scopus, Embase, Web of Science, and Google Scholar were used as international databases from inception to May 2022. To examine the effects of n-3 PUFA supplementation on blood pressure, a random-effects model was applied. The leave-one-out method was performed for the sensitivity analysis. The pooled estimate of 10 meta-analyses with 20 effect sizes revealed significant reductions in both systolic (ES = −1.19 mmHg; 95% CI: −1.76, −0.62, p < 0.001) and diastolic blood pressure (ES = −0.91 mmHg, 95% CI: −1.35, −0.47; p < 0.001) following n-3 PUFAs supplementation. In studies with a sample size of ≤ 400 participants and a mean age over 45, SBP and DBP were found to be substantially reduced. Overall, this umbrella meta-analysis indicates that n-3 PUFAs supplementation might play a role in improving DBP and SBP.