Background Soluble dietary fibers are known to reduce the levels of blood glucose
and lipids in patients with type 2 diabetes mellitus (type 2 diabetes). Although several
different dietary fiber supplements are utilized, to our knowledge, no previous study
has ranked their efficacy yet. Objectives We performed this systematic review and
network meta-analysis to rank the effects of different types of soluble dietary fibers.
Methods We performed our last systematic search on November 20, 2022. Eligible randomized
controlled trials (RCTs) included adult patients with type 2 diabetes and compared
the intake of soluble dietary fibers with that of another type of dietary fiber or
no fiber. The outcomes were related to glycemic and lipid levels. The Bayesian method
was used to perform a network meta-analysis and calculate the surface under the cumulative
ranking (SUCRA) curve values to rank the interventions. The Grading of Recommendations
Assessment, Development, and Evaluation system was applied to evaluate the overall
quality of the evidence. Results We identified 46 RCTs, including data from 2685 patients
who received 16 types of dietary fibers as intervention. Galactomannans had the highest
effect on reducing the levels of HbA1c (SUCRA: 92.33%) and fasting blood glucose (SUCRA:
85.92%). With regard to fasting insulin level, HOMA-IR, β-glucans (SUCRA: 73.45%),
and psyllium (SUCRA: 96.67%) were the most effective interventions. Galactomannans
were ranked first in reducing the levels of triglycerides (SUCRA: 82.77%) and LDL
cholesterol (SUCRA: 86.56%). With regard to cholesterol and HDL cholesterol levels,
xylo-oligosaccharides (SUCRA: 84.59%) and gum arabic (SUCRA: 89.06%) were the most
effective fibers. Most comparisons had a low or moderate certainty of evidence. Conclusions
Galactomannans were the most effective dietary fiber for reducing the levels of HbA1c,
fasting blood glucose, triglycerides, and LDL cholesterol in patients with type 2
diabetes. This study was registered at PROSPERO as ID CRD42021282984.
