Gastric bypass improves subclinical nephropathy in non-severely obese patients (BMI < 35 kg/m2) with type 2 diabetes mellitus

Introduction: Bariatric surgery results in high remission rates of type 2 diabetes mellitus (T2DM) in obese patients. We have previously shown that Roux-en-Y gastric bypass (RYGB) improves diabetic neuropathy, likely due to a reduction in nitrosative stress. The purpose of this study was to investigate whether RYGB is also able to improve diabetic nephropathy. Methods: Twenty consecutive patients with a body mass index (BMI) between 25 – 35 kg/m2 and a poorly controlled, insulin-dependent T2DM were enrolled. All patients were treated with a standardized RYGB. Changes in serum creatinin levels, urinary albumin excretion and total serum adiponectin were collected. High-molecular weight (HMW) adiponectin as a sensitive marker for nephropathy was measured in serum and urinary samples using ELISAs. Data are presented as mean ± SEM. Results: Over the 24 month follow-up period, serum creatinin levels decreased within 3 months from 0.82 ± 0.05 mg/dl to 0.67 ± 0.03 mg/dl (p < 0.05) and remained at these levels. The urinary albumin/creatinin ratio started decreasing within 3 months and reached significantly lower levels after 6 months (2.38 ± 0.86 mg/mmol to 1.15 ± 0.17 mg/mmol, p < 0.05). Similarly, urinary HMW adiponectin decreased over the 24 month follow-up period (0.185 ± 0.074 ng/ml to 0.074 ± 0.014 ng/ml, p < 0.05). In contrast, total serum adiponectin showed a significant increase over the same period whereas serum HMW adiponectin did not change. Conclusion: RYGB appears to improve microvascular complications of T2DM such as subclinical nephropathy and neuropathy in non-severely obese patients. Further research should investigate by which mechanisms diabetic nephropathy is improved in these patients.