Do Probiotics Prevent Gestational Diabetes in Obese/Overweight patients? A Systematic Review

Introduction: While some studies suggest probiotic supplements may prevent Gestational Diabetes Mellitus (GDM), it is unclear if probiotics effectively prevent GDM among overweight and obese patients. This systematic review synthesizes recommendations for clinical practice and future research by evaluating the quality of evidence regarding Lactobacillus and Bifidobacterium containing probiotics to prevent GDM among obese and overweight patients. Methods: PubMed, Embase, CINAHL, and Web of Science were searched using appropriate MeSH terms. Results were limited to randomized controlled trials published between 2011 and 2021. Titles and abstracts were screened for relevance after duplicates were removed. The inclusion criteria were as follows: studies that diagnosed GDM according to the International Association of Diabetes and Pregnancy Study Group criteria, suspended probiotic use prior to intervention, excluded participants with altered glucose metabolism, included participants with a body mass index ≥ 25 kg/m 2 , and provided a specified dose of probiotic supplements. Articles without statistical analysis were excluded. Resulting articles were critically appraised using Version 2 of the Cochrane Risk of Bias tool. Results: This search strategy resulted in 24 articles after duplicates were removed. Five double-blind randomized controlled trials found that the incidence of GDM during the third trimester was not significantly different between probiotic and control groups. There was wide variation in the bacterial species, dose, and duration of probiotic treatments used. All studies have a high risk of bias due to non-adherence to the treatment. Discussion: This review used highly sensitive criteria for GDM diagnosis that may mask a preventative effect of probiotics. Noncompliance may bias results toward the null, given insufficient analysis of the effect of adhering to the intervention. No patterns between the length of probiotic intervention or probiotic species and improved glucose tolerance were noted. Conclusions: Current evidence is not sufficient to recommend probiotic supplements to prevent GDM in overweight and obese patients. Future evidence should address the effect of adhering to probiotic interventions and develop consistent probiotic intervention protocols.