Effect of viscous soluble dietary fiber on glucose and lipid metabolism in patients with type 2 diabetes mellitus: a systematic review and meta-analysis on randomized clinical trials

Background: The effect of viscous soluble dietary fiber on glucose and lipid metabolism in type 2 diabetes mellitus (T2DM) remains controversial, and the dose-response relationship of its effect on blood glucose and blood lipid level is still unclear.Methods: We conducted comprehensive searches in several databases up to 17 January 2023. We conducted a dose-response analysis of randomized controlled trials (RCTs) to investigate the effect of viscous dietary fiber on glucose and lipid metabolism in patients with T2DM.Results: Statistical significance was observed in the decreases of glycosylated hemoglobin (HbA1c) (mean difference) [MD = -0.47; 95%CI: (-0.66, -0.27)], fasting blood glucose (FBG) [MD = -0.93; 95%CI: (-1.46, -0.41)], total cholesterol (TC) [MD = -0.33; 95%CI: (-0.46, -0.21)], and low-density lipoprotein and cholesterol (LDL-C) [MD = -0.24; 95%CI: (-0.35, -0.13)]. Contrarily, no difference was observed regarding the level of high-density lipoprotein cholesterol (HDL-C) or triglyceride (TG). In addition, the effect on fasting insulin remains unclear. Results from the subgroup analyses showed that an intervention duration longer than 6 weeks had a significant effect on the HbA1c level; a treatment dosage higher than 8.3 g/day had a significant effect on the FBG level.Conclusions: Supplementation of viscous dietary fiber is beneficial to control blood glucose and blood lipid in T2DM.