Abstract Context The type of dietary protein may modulate markers of diabetic kidney disease; however, no attempt to summarize the evidence from randomized controlled trials (RCTs) has been performed to date. Objective To assess the effects of different types of dietary protein on urinary albumin excretion and glomerular filtration rate in individuals with diabetes. Data sources MEDLINE, EMBASE, and Scopus were searched for all published RCTs, with no language restriction, up to July 2020. Data Extraction Study selection and data extraction were performed independently by 3 authors. Risk of bias was assessed independently by 2 authors, and the GRADE approach was used to assess the quality of the evidence. Results Twelve RCTs were included, of which 11 (involving 228 participants) were compiled in meta-analyses of random-effects models. Interventions consisted of diets emphasizing plant or white meat protein, with reduced intake of animal or red meat protein. Pooled data from crossover trials (n = 8) favored intervention diets for urinary albumin excretion (ratio of means, 0.86; 95% confidence interval 0.80 to 0.94; I2 = 4%) and glomerular filtration rate (ratio of means, 0.90; 95% confidence interval 0.87 to 0.94; I2 = 45%), compared with control diets. Results from parallel-design studies (n = 3), however, were not statistically significant for any outcome. The quality of the evidence ranged from very low to moderate, and most studies were judged with at least some concerns in terms of risk of bias. Conclusion This meta-analysis found weak evidence for small to moderate improvements in markers of kidney function in favor of interventions with lower animal protein (or red meat protein) compared with usual diets in short-term crossover trials. These findings require confirmation in well-designed randomized controlled trials.