The efficacy of dietary interventions for prediabetes management: An umbrella review of meta-analyses

Literature suggested that prediabetes may be reversible through dietary interventions. Despite numerous meta-analyses evaluating the efficacies of dietary intervention strategies, there is a lack of umbrella review to gather published meta-analyses, then to assess their reliability and strength of evidence. Meta-analyses of randomized controlled trials (RCTs) on dietary interventions for adults with prediabetes were collected from Embase, Emcare, MEDLINE, Ovid Nursing, and CNKI. Meta-analyses with at least 3 independent RCTs were selected to re-estimate random-effects pooled effect sizes. Credibility of evidence was assessed using AMSTAR 2 and NutriGrade. Nine meta-analyses comprising 45 comparisons and 10,814 participants were included. Among the dietary interventions examined, Vitamin D supplementation led to reduced fasting blood glucose (SMD: -0.377, 95 % CI: -0.598 to -0.165), decreased blood triglycerides (SMD: -0.385, 95 % CI: -0.622 to -0.147), reduced risk of T2D onset (RR: 0.897, 95 % CI: 0.810-0.994), and increased likelihood of reverting to normoglycemia (RR: 1.238, 95 % CI: 1.074-1.425). Prebiotic supplementation significantly reduced body fat (SMD: -1.271, 95 % CI: -2.326 to -0.216). Fructose replacement significantly reduced postprandial plasma glucose levels compared to glucose (SMD: -8.275, 95 % CI: -12.663 to -3.887) and sucrose (SMD: -5.176, 95 % CI: -9.558 to -0.793). However, the credibility of the evidence was limited by small sample sizes and heterogeneity. While several dietary interventions that improve cardiometabolic health of individuals with prediabetes were identified, the credibility of evidence is weak. There is a need for future large-scale, long-term, and high-quality trials in this population. PROSPERO CRD42024506257.