Effects of bariatric surgery on diabetic nephropathy after 5 years of follow-up

Background: Studies have reported that the benefits of bariatric surgery extend beyond durable weight loss and include significant improvement in glycemic control. We hypothesized that improving diabetes control may have positive effects on end-organ complications of this disease, such as diabetic nephropathy (DN). Methods: We identified all patients with type 2 diabetes mellitus (T2DM) who underwent bariatric surgery at our institution and had completed a 5-year follow-up. Patients' current diabetes status (remission, improvement, or no change) was determined by biochemical analyses and medication review. The presence of DN, preoperatively and postoperatively, was determined by urinary albumin/creatinine ratio (uACR). Results: Fifty-two T2DM patients underwent bariatric surgery and had completed 5-year follow-up, including serial uACR measurements (25% male; age 51.2 +/- 10.1 years). Preoperative body mass index (BMI) was 49 +/- 8.7 kg/m(2), mean duration of T2DM was 8.6 years (range .3-39), and baseline HbA(1c) was 7.7% +/- 1.4%. DN, as indicated by microalbuminuria (30-300 mg/g) or macroalbuminuria (>300 mg/g), was present in 37.6% preoperatively. Of these, DN resolved in 58.3% at a mean follow-up of 66 months (range 60-92). Among those with no evidence of DN preoperatively, albuminuria proceeded to develop 5 years later in only 25%. The 5-year remission and improvement rates for T2DM were 44% and 33%, respectively. Mean reductions in fasting glucose and glycosylated hemoglobin (HbA(1c)) were 36.6 mg/dL and 1.2%, respectively. Conclusion: Bariatric surgery can induce a significant and sustainable improvement in T2DM and improve or halt the development of microvascular complications such as nephropathy. Considering that diabetes is often a progressive disease, these results are clinically important and warrant further investigation. (Surg Obes Relat Dis 2013;9:7-14.) (C) 2013 American Society for Metabolic and Bariatric Surgery. All rights reserved.