Effect of Barley Intervention on Glycemic Control and Insulin Sensitivity in Adults: A Systematic Review and Meta-Analysis of 31 Controlled Trials

Context Dysregulated blood glucose levels and insulin resistance are key contributors to various metabolic complications and increased mortality. Among lifestyle interventions, dietary modification is a crucial strategy for improving glucose tolerance. Barley, rich in fiber and β-glucan, may offer a promising dietary approach for glycemic control. Objective To evaluate the impact of barley intake on short- and long-term glycemic and insulin responses through a systematic review and meta-analysis. Data Sources Through comprehensive searches in major scientific databases, 31 controlled trials with 34 intervention arms were identified, including a total of 660 case patients and 665 control participants. Data Extraction Two reviewers independently extracted data, and a random-effects model was used to calculate pooled estimates of outcomes. Results Barley supplementation significantly reduced postprandial glucose levels at 30 (−10.48 mg dL–1), 60 (−12.38 mg dL–1), and 120 (−6.95 mg dL–1) minutes; however, no significant effects were observed at 180 minutes. Barley supplementation significantly reduced postprandial insulin levels at 30 (−6.02 pmol L–1), 60 (−12.83 pmol L–1), and 180 (−5.89 mg dL–1) minutes; however, no significant effects were observed at 120 minutes. No significant changes in insulin levels were observed beyond the early postprandial period. In the long term, barley intake did not significantly affect fasting glucose or hemoglobin A1c levels. Conclusions This meta-analysis supports the short-term benefits of barley consumption in improving early postprandial glucose and insulin responses. No significant impact was found on later or long-term glycemic markers. More high-quality trials are needed to confirm these outcomes. Systematic Review Registration PROSPERO registration No. CRD42022368122