Microvascular Outcomes in Patients With Diabetes After Bariatric Surgery

Abstract

TO THE EDITOR: O Brien and colleagues (1) reported that bariatric surgery reduces the risk for microvascular disease in patients with types 2 diabetes. Their findings will help health care professionals and patients who are considering bariatric surgery make decisions on the basis of more accurate information. However, the cubic spline plot in Figure 2 of their article shows that, unlike other microvascular diseases, the risk for diabetic nephropathy in the surgery group increased immediately after bariatric surgery compared with that in the control group. However, the authors did not adequately discuss this finding. Our research team is currently performing a systematic review of changes in renal function or renal injuries after bariatric surgery. Among 4 studies that measured proteinuria in the early postoperative period, 2 reported that the urinary protein concentration remained consistent with or actually increased compared with levels before surgery (2, 3). These 2 studies included results of 1-month follow-up after sleeve gastrectomy and Roux-en-Y gastric bypass in obese patients without diabetes. The early postoperative period until 6 months after bariatric surgery is characterized by rapid weight loss as well as rapid changes in inflammatory activities and hemodynamic measurements in the kidneys, which may cause obesity-induced kidney injury (4, 5). These conditions are suspected to increase the risk for proteinuria immediately after bariatric surgery in some patients with or without type 2 diabetes who have indications for this surgery. If a specific group clearly has an increased risk for diabetic nephropathy immediately after bariatric surgery, which O Brien and colleagues study shows, the authors should present the appropriate data and discuss that group.