Prediabetes is associated with metabolic disturbances that significantly increase the risk of developing cardiovascular disease (CVD). Probiotics and synbiotics may improve metabolic health, but their impact on CVD risk factors in prediabetic adults needs further evaluation. This meta-analysis evaluates the effects of probiotic and synbiotic supplementation on cardiovascular risk factors in individuals with prediabetes.

Methods: An extensive search of scientific databases was conducted from inception through February 2025 to identify relevant randomized controlled trials (RCTs). After screening, data were extracted. A random-effects model was used to compute pooled weighted mean differences (WMD) with 95% confidence intervals (CIs), accounting for study heterogeneity. All statistical analyses were performed using Stata.

Results: The pooled analysis of seven RCTs revealed that probiotics and synbiotics supplementation in prediabetic adults had no significant changes in fasting blood glucose (FBG) (WMD: -2.15 mg/dL, p = 0.135), fasting insulin (FI) (WMD: -0.43 µIU/mL, p = 0.526), Homeostasis model assessment of insulin resistance (HOMA-IR) (WMD: -0.31, p = 0.090), triglycerides (TG) (WMD: -5.53 mg/dL, p = 0.614), total cholesterol (TC) (WMD: -1.92 mg/dL, p = 0.730), low-density lipoprotein cholesterol (LDL-C) (WMD: 1.39 mg/dL, p = 0.542), systolic blood pressure (BP) (WMD: -2.24 mmHg, p = 0.480), diastolic BP (WMD: -1.10 mmHg, p = 0.260), body weight (WMD: 0.30 kg, p = 0.861), and body mass index (BMI) (WMD: -0.20 kg/m², p = 0.510). In contrast, a significant improvement was noted in hemoglobin A1c (HbA1c) levels (WMD: -0.16, p < 0.001) and high-density lipoprotein cholesterol (HDL-C) (WMD: 1.63 mg/dL, p = 0.020).