Search strategy in different databases.

<div><p>Background</p><p><i>Diabetes mellitus</i> (DM) is characterized by hyperglycemia due to insufficient insulin production or utilization. Previous studies have shown a relationship between the gut microbiota and DM, driving interest in probiotic supplementation to modulate the microbiota and glucose metabolism in patients with DM, although the exact mechanisms remain unclear. Probiotics can influence metabolic factors and improve the composition of the microbiota, possibly helping to reduce weight in patients with DM.</p><p>Objective</p><p>The objective of this review is to compile and analyze the most relevant evidence on the effects of probiotic supplementation on the nutritional anthropometric status of patients with type 2 Diabetes mellitus (T2DM).</p><p>Methods</p><p>Methodological guidelines will be followed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement and the study has been registered in the International Prospective Register of Systematic Reviews under reference number CRD42023480243. Studies will be selected through an active search of the PubMed, Science Direct, and SCOPUS databases using the following search descriptors: gut microbiota, body weight, and metabolic diseases, according to medical subject headings. The assessment of the methodological quality of the studies will be carried out using the Cochrane Collaboration instrument. The risk of bias will be analyzed using the Revised Cochrane tool for risk of bias in randomized controlled trials (RoB 2). A meta-analysis will be performed if heterogeneity is acceptable and justifiable; otherwise, the results will be presented in a qualitative narrative synthesis.</p><p>Expected results</p><p>The results of probiotic supplementation are expected to demonstrate improvements in anthropometric parameters such as body weight, BMI and abdominal and waist circumference in patients with T2DM, thus providing valuable evidence for clinical application.</p></div>