Effects of fish oil intervention on type 2 diabetes early risk novel biomarkers in healthy middle-aged and elderly adults: a double-blind randomized controlled trial

Objective: Recent studies on type 2 diabetes (T2D) have identified several novel biomarkers that demonstrate greater stability compared to traditional blood glucose indicators. This trial aimed to investigate the effect of fish oil intervention on these T2D early risk novel biomarkers. Methods: We conducted a 12-week double-blind randomized controlled trial, the healthy middle-aged and elderly participants over 40 years old were randomly divided into the control group, fish oil group 1 (FO1), fish oil group 2 (FO2), and fish oil group 3 (FO3), with each FO group receiving 0.31, 0.62, and 1.24 g of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), respectively. The control group abstained from consuming any fish oil supplements. At week 12, serum samples were collected and compared with the control group to explore the effects of different doses on serum n-3 polyunsaturated fatty acids (PUFAs) and T2D early risk novel biomarkers. Results: A total of 240 participants were recruited into this double-blind randomized controlled trial, and 201 finally completed the intervention trial, including 57 males and 144 females. The results indicate that after controlling for relevant confounders, a 12-week fish oil intervention dose-dependently increased serum EPA and DHA, while decreasing fasting insulin (FINS), HOMA-IR index (P < 0.01). Concurrently, fasting blood glucose (FBG) exhibited a downward trend across all groups, with significant differences compared with the baseline (P < 0.01); mannan-binding lectin serine protease 1 (MASP1), UA to high-density lipoprotein cholesterol (HDL-C) ratio (UHR) and lipid-related indices in various groups also demonstrated a decreasing trend, with significant differences compared with the baseline (P < 0.05). Conclusion: Moderate supplementation with fish oil may diminish the early risk of T2D in healthy middle-aged and elderly adults by enhancing insulin sensitivity, and maintaining insulin homeostasis.