Should Viscous Fiber Supplements Be Considered in Diabetes Control? Results From a Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE Evidence from randomized controlled trials (RCTs) suggests that viscous dietary fiber may offer beneficial effects on glycemic control and, thus, an improved cardiovascular disease risk profile. Our purpose was to conduct a systematic review and meta-analysis of RCTs to synthesize the therapeutic effect of viscous fiber supplementation on glycemic control in type 2 diabetes. RESEARCH DESIGN AND METHODS MEDLINE, Embase, and Cochrane Central Register of Controlled Trials were searched through 15 June 2018. We included RCTs ≥3 weeks in duration that assessed the effects of viscous fiber on markers of glycemic control in type 2 diabetes. Two independent reviewers extracted data. Data were pooled using the generic inverse variance method and expressed as mean differences (MD) with 95% CIs. Heterogeneity was assessed (Cochran Q statistic) and quantified ( I 2 statistic). The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to evaluate the overall certainty of the evidence. RESULTS We identified 28 eligible trial comparisons ( n = 1,394). Viscous fiber at a median dose of ∼13.1 g/day significantly reduced HbA 1c (MD −0.58% [95% CI −0.88, −0.28]; P = 0.0002), fasting blood glucose (MD −0.82 mmol/L [95% CI −1.32, −0.31]; P = 0.001), and HOMA-insulin resistance (IR) (MD −1.89 [95% CI −3.45, −0.33]; P = 0.02) compared with control and in addition to standard of care. The certainty of evidence was graded moderate for HbA 1c , fasting glucose, fasting insulin, and HOMA-IR and low for fructosamine. CONCLUSIONS Viscous fiber supplements improve conventional markers of glycemic control beyond usual care and should be considered in the management of type 2 diabetes.