Effect of Roux-En-Y Gastric Bypass on Albuminuria in Morbidly Obese Patients with Type-2 Diabetes Mellitus: A Prospective Non-Randomized Controlled Study with 15-Month Follow-Up

Background: Obesity increases the risk of chronic kidney disease and has been linked to proteinuria and albuminuria. Roux-en-Y gastric bypass (RYGB) plays a significant role in the treatment of obesity and type-2 diabetes mellitus (T2DM). This study aimed to examine the effect of RYGB on albuminuria in patients with morbid obesity and T2DM. Methods: This prospective, non-randomized, controlled study included two groups of patients with morbid obesity and T2DM; allocation was by patient preference rather than randomization. The RYGB Group (n = 64) underwent RYGB, and the Control Group (n = 58) received conservative (lifestyle) measures only. Micro- and macroalbuminuria were determined from spot urine albumin-to-creatinine ratio (uACR) on a first-morning urine sample. Patients were monitored for 15 months for remission and improvement of albuminuria. Groups were compared using the independent-sample t -test, Mann–Whitney test, or chi-square test as appropriate, and multivariable logistic regression was used to adjust for baseline differences. Results: The groups differed significantly at baseline in age, body mass index (BMI), HOMA-IR index, LDL-cholesterol, and ALT. RYGB achieved a significantly (p < 0.001) greater rate of albuminuria remission (57.8%) than diet control (24.1%). None of the baseline characteristics were associated with albuminuria remission except lower baseline triglyceride (p = 0.012) and LDL-cholesterol (p = 0.040) levels. Albuminuria remission was associated with significantly greater weight loss (p = 0.003) and lower BMI (p = 0.019), fasting plasma insulin (p = 0.014), HOMA-IR (p = 0.011), total cholesterol (p = 0.026), LDL-cholesterol (p = 0.001), ALT (p = 0.033), and AST (p = 0.009). After adjustment for baseline differences, RYGB remained the only independent predictor of albuminuria remission (adjusted odds ratio 3.27, 95% CI 1.23– 8.67; p = 0.017). Conclusion: In this non-randomized cohort, RYGB was associated with a significantly higher rate of albuminuria remission than lifestyle intervention over 15 months. Remission was associated with greater weight loss, lower plasma insulin, and improved insulin sensitivity rather than with diabetes remission itself. Randomized or better-adjusted prospective studies are warranted to confirm these findings.