Omega-3 index and type 2 diabetes: Systematic review and meta-analysis

Background and Objectives: The relationship between omega-3 index and type 2 diabetes (T2D) is not well established. It is unclear if the change of omega-3 index will affect T2D. Aiming of the present systematic review was to elucidate the correlation between omega-3 index and T2D. Methods and Study Design: A comprehensive search on PubMed, EMBASE and Web of Science (from 1948 to May 2021) was conducted. The overall effect size (standard mean difference) was combined using a random-effect model. Results: Eight eligible case-control studies were identified, and there were 1,357 patients with T2D and 1,616 non-diabetic controls. The result showed that the omega-3 index was significantly lower in diabetic cases than that in controls (SMD= -1.31; 95% confidence interval (CI): -1.40, -1.22), but with significant heterogeneity (I2 = 99.0%). In subgroup analysis based on race, a negative correlation was found in Asians (SMD = -1.71; 95% CI: -1.82, -1.60), and heterogeneity was substantially decreased (I2=0). Conclusions: omega-3 index is negatively correlated with T2D, which indicated that increased dietary intake of omega-3 fatty acids might have beneficial on T2D prevention.