Weight loss independently predicts urinary albumin excretion normalization in morbidly obese type 2 diabetic patients undergoing bariatric surgery

Despite obesity being closely associated with two common risk factors for albuminuria, namely type 2 diabetes mellitus (T2DM) and hypertension, information on the impact of weight loss on albumin excretion rate in morbidly obese (MO) subjects is scarce. To evaluate the independent contribution of weight loss following bariatric surgery (BS) to the improvement of the albumin-to-creatinine ratio (ACR) in MO subjects with T2DM. Observational prospective study, including consecutive (n = 255) patients undergoing Roux-en-Y gastric bypass (GBP) or sleeve gastrectomy (SG) of whom 37.6 % (n = 96) presented with T2DM. Stepwise logistic regression analysis was used to assess the contribution of T2DM-related, hypertension-related, and weight loss-related variables, and type of surgery to normalization of ACR (< 30 mg/g) at 12 and 24 months follow-up. In T2DM subjects, baseline ACR was 85.7 +/- A 171 mg/g with ACR a parts per thousand yen30 mg/g being present in 45.7 % of the cohort. At 12 months, the ACR significantly decreased in T2DM subjects (42.2 +/- A 142.8 mg/g; p < 0.005) with no further reduction at 24 months after surgery (44.4 +/- A 227.7; p = 0.862). Among T2DM subjects with ACR a parts per thousand yen30 mg/g at baseline, the ACR became < 30 mg/g in 58.5 % and 76.9 % at 12 and 24 months, respectively (p < 0.001 relative to baseline). Body mass index (BMI) change from baseline was the only independent predictor of ACR normalization at 12 months [Exp(B) 1.373, 95 % confidence interval 1.075-1.703; p < 0.05]. None of the evaluated variables appeared as an independent predictor of ACR normalization at 24 months. Our data suggest that, in MO subjects with T2DM, interventions aiming at slowing the progression of nephropathy should not only focus on optimization of glucose and blood pressure control but also include effective weight loss strategies.