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Role of Whole Grain Consumption in Glycaemic Control of Diabetic Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

ABSTRACT:

Background

Observational studies have indicated beneficial effects of whole grain consumption on human health. However, no evidence based on randomized controlled trials has been established. Our objective was to perform a systematic review and meta-analysis of randomized controlled trials to assess the effects of whole grain consumption in glycaemic control of diabetic patients.

Methods

A comprehensive search in four databases (Web of Science, Pubmed, Scopus and Cochrane library) was conducted to collect potential articles which measured the roles of whole grain consumption on glycaemic control up to October 2021.

Results

A total of 16 eligible trials involving 1068 subjects were identified to evaluate the pooled effect. The overall results indicated that compared with the control group, whole grain intake presented a significantly reduced concentration in fast plasma glucose (WMD = -0.51 mmol/L, 95% CI: -0.73, -0.28; I2 = 88.6%, p < 0.001), a homeostasis model assessment of insulin resistance (WMD = -0.39 μU × mol/L², 95% CI: -0.73, -0.04; I2 = 58.4%, p = 0.014), and glycosylated haemoglobin (WMD = -0.56%, 95% CI: -0.88, -0.25, I2 = 88.5%, p < 0.001), while no significant difference was observed in fast plasma insulin level between groups (SMD = -0.05, 95% CI: -0.25, 0.14; I2 = 40.7%, p = 0.120). In terms of incremental area under the curve (iAUC), data suggested that whole grain effected a significant decrease in Glucose-iAUC (WMD = -233.09 min × mmol/L, 95% CI: -451.62, -14.57; I2 = 96.1%, p < 0.001) and Insulin-iAUC (SMD = -4.80, 95% CI: -8.36, -1.23; I2 = 89.9%, p = 0.002), although only in a small number of studies. Of note, there is evidence for modest unexplained heterogeneity in the present meta-analysis.

Conclusion

Whole grain consumption confers a beneficial effect on glucose metabolism in patients with diabetes. Regrettably, since relevant studies were scarce, we failed to provide confident evidence of whole grain consumption on acute effects including Glucose-iAUC and Insulin-iAUC, which should be addressed in further trials.

SUBMITTER: Xu D

PROVIDER: S-EPMC8746707 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Since the release of a previous meta-analysis on the effect of whole-grain intake on obesity measures, several clinical trials have been published. Therefore, we aimed to update the previous meta-analysis on the effect of whole-grain intake on obesity measures by including recently published studies, as well as considering the main limitations in that analysis. We searched the online databases of PubMed, Scopus, Clarivate Web of Science, EmBase, and Google Scholar for relevant studies published up to February 2019, using relevant keywords. Randomized clinical trials investigating the effect of whole-grain products or diets high in whole-grain foods, compared with a control diet, on anthropometric measures [including body weight, BMI, waist circumference, and fat mass (FM)] were included. In total, 21 studies with a total sample of 1798 participants, aged ?18 years, were considered. Based on 22 effect sizes from 19 studies on body weight, with a total sample of 1698 adults, we found no significant effect of whole-grain consumption on body weight. The same findings were obtained for BMIs, such that using 10 effect sizes from 10 clinical trials with a total sample of 769 individuals we did not find any significant effect. With regards to body fat percentage [weighted mean difference (WMD): 0.27; 95% CI: -0.05 to 0.58%; P = 0.09], FM (WMD: 0.45; 95% CI: -0.12 to 1.02 kg; P = 0.12), fat-free mass (WMD: 0.31; 95% CI: -0.67 to 0.06 kg; P = 0.10), and waist circumference (WMD: 0.06; 95% CI: -0.50 to 0.63 cm; P = 0.82), we failed to find any significant effect of whole-grain consumption. In conclusion, our findings did not support current recommendations of whole-grain intake in attempts to control obesity measures. Given the beneficial effects of whole-grain intake on other measures of human health, additional well-designed studies are required to further investigate the effect on obesity. The protocol has been registered with PROSPERO (registration number CRD42019125320).

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