Bariatric surgery reduces urinary albumin excretion in diabetic nephropathy: a systematic review and meta-analysis

Background: Bariatric surgery is found to prevent type 2 diabetes, improve glycemic control, and decrease long-term incidence of macrovascular and macrovascular complications in obese persons. However, its effect on urinary albumin excretion (UAE) in patients with diabetic nephropathy (DN) is still unknown. This is a systematic review and meta-analysis of observational studies on bariatric surgery and change in UAE in patients with diabetes. Objective: To explore whether there is improvement in UAE after bariatric surgery. Methods: We comprehensively searched the databases of MEDLINE, Embase, and Cochrane. The inclusion criteria were published studies evaluating effects of bariatric surgery in patients with DN at baseline. The primary outcome was the pre- and postbariatric surgery UAE as characterized by urinary albumin-to-creatinine ratio and albuminuria. A meta-analysis comparing pre- and post surgery UAE was performed. Results: From 65 full-text articles, 15 observational studies met our inclusion criteria, and 11 studies were included in the meta-analysis based on the random effects model. There was a significant reduction in urinary albumin-to-creatinine ratio after bariatric surgery with a mean difference of 6.60 mg/g of creatinine (95% CI -9.19 to -4.02; P <.001). There was also a reduction in albuminuria with a mean difference of -55.76 mg/24 hours (95% CI -92.11 to -19.41; P <.001) after bariatric surgery. Conclusion: Bariatric surgery significantly decreases urinary albumin excretion in DN. However, studies comparing bariatric surgery and conventional or intensive care of diabetes on UAE outcome should be done. (C) 2016 American Society for Metabolic and Bariatric Surgery. All rights reserved.