What is the impact of oral probiotic supplementation on the HOMA-IR insulin resistance index in pregnant women with gestational diabetes mellitus without antidiabetic medication during the current pregnancy? A systematic review and meta-analysis

Background Gestational diabetes mellitus (GDM) is a common pregnancy complication, with an estimated global prevalence of up to 14%. While lifestyle and genetic risk factors for GDM are well documented, the effect of probiotic supplementation on the management of GDM-specifically through the reduction of insulin resistance as measured by the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) index-has not been systematically evaluated. Objective This meta-analysis aimed to quantitatively evaluate the clinical efficacy of probiotic supplementation in reducing the HOMA-IR index in a population of pregnant women with diagnosed GDM who manage the disease without the use of antidiabetic pharmacotherapy (insulin or oral agents), as well as to address the probiotics as an evidence-based, adjunctive therapeutic strategy for a more effective regulation of the metabolic profile during pregnancy. Methods PubMed, Scopus, and Cochrane databases were searched for original research articles published up to August 10, 2025, which could potentially evaluate the impact of oral probiotic supplementation to the reduction of the HOMA-IR insulin resistance index in pregnant women with GDM without antidiabetic medication during the current pregnancy. A random-effects model was applied to estimate weighted mean differences (MDs) and 95% confidence intervals (CIs). Results Four randomized controlled trials comprising 245 women (128 in the probiotic group and 126 in the placebo group) were included. The meta-analysis demonstrated a statistically significant reduction in the HOMA-IR levels in the intervention group compared to the control group (weighted MD: -0.51, 95% CI: -0.90 to -0.11, p = 0.01). Significant heterogeneity was observed among the studies (I 2 = 61.3%). Conclusion The administration of probiotics appears to improve insulin sensitivity in women with GDM and may serve as a useful adjunctive therapy.