Objective: To conduct a Meta-analysis of the effects of whole grains on insulin resistance in overweight and obese adults in randomize controlled trials.
Methods: Data were retrieved from PubMed, EMBASE, MEDLINE, Cochrane Library, CBM, CNKI and other databases from the database establishment to August 9, 2021. Randomize controlled trials of the effects of whole grains on insulin resistance in overweight and obese adults were screened out. Data extraction and quality evaluation were conducted for the literatures meeting the inclusion criteria. The Meta-analysis was conducted using R4.1.2 software.
Results: A total of 10 randomized controlled trials were included. Among the overweight and obese adults, the whole grains intake decreased their fasting plasma glucose(FPG)(MD=-0.08, 95%CI-0.12, -0.04), homeostasis model assessment of insulin resistance(HOMA-IR)(MD=-0.37, 95%CI-0.60, -0.14) and quantitative insulin sensitivity index(QUICKI)(MD=0.006, 95%CI 0.005, 0.007). However, there were no statistically significant among fasting insulin(FINS), postprandial blood glucose(PG), postprandial insulin(PI), and triglycerides(TG) in overweight and obese adults. In subgroup analysis, FPG was statistically significant in German, quality score 4, 150-200 g intake of whole grain, and health subgroups of each population. There was no statistical significance of the QUICKI group. In sensitivity analysis and publication bias, FINS, PG, PI and TG became significant after one article was removed. However, HOMA-IR result were not statistically significant after the removal of one article. Meanwhile, the publication bias of each index was analyzed by Egger regression. Based on the results of subgroup analysis, a further dose-response analysis was conducted on the whole grains intake. The result showed that the FPG effects scale was better when the daily intake of whole grains was between 140 g and 160 g.
Conclusion: Daily intake of 140 g to 160 g of whole grains improves FPG levels in overweight and obese adults.
Keywords: Meta-analysis; insulin resistance; overweight and obese; randomized controlled trial; whole grains.