Effects of probiotic supplementation on diabetic kidney disease: a systematic review and meta-analysis of randomized controlled trials

Background Diabetic kidney disease (DKD) is one of the leading causes of end-stage kidney disease worldwide, and microbiota-based interventions are considered potential preventive and therapeutic strategies to slow its progression. This study evaluated the efficacy of probiotic supplementation in patients with DKD through a systematic review and meta-analysis. Methods We searched seven databases, including PubMed, Embase, the Cochrane Library (CENTRAL), CNKI, Wanfang, VIP and SinoMed, to identify all relevant studies published from database inception to July 2025. Eligible studies were randomized controlled trials assessing probiotic interventions in DKD patients. Study quality was evaluated using the Cochrane Risk of Bias tool, and meta-analyses were performed using R. Results A total of 11 studies involving 726 participants were included. Probiotic supplementation significantly improved serum creatinine (MD − 0.17, −0.22 to −0.12, p 0.0001) and estimated glomerular filtration rate (MD 9.62, 2.74 to 16.51, p 0.0001). No significant effects were observed for blood urea nitrogen, urinary albumin-to-creatinine ratio, 24-h urinary protein or cystatin C. Probiotics also showed notable benefits in glycemic and lipid parameters, including reductions in fasting plasma glucose (MD − 18.52, −27.08 to −9.97, p 0.0001), glycated hemoglobin (MD − 0.18, −0.31 to −0.05, p = 0.009), and homeostasis model assessment of insulin resistance (MD − 1.22, −2.01 to −0.43, p = 0.002), as well as an increase in high-density lipoprotein cholesterol (MD 5.45, 1.08 to 9.83, p = 0.01). In addition, probiotic supplementation led to significant reductions in inflammatory and oxidative stress markers, including high-sensitivity C-reactive protein (MD − 1.53, −2.38 to −0.69, p = 0.0004) and malondialdehyde (MD − 0.81, −0.97 to −0.65, p 0.0001), and a significant increase in total antioxidant capacity (MD 62.71, 41.80 to 83.62, p 0.0001). Conclusion Probiotic supplementation may improve metabolic disturbances, renal function, and systemic inflammation/oxidative stress in DKD patients. However, its clinical efficacy and long-term effects require further validation in large-scale studies.