Does weight-loss surgery improve diabetic kidney disease?

This study looked at how gastric bypass weight-loss surgery affects kidney function for patients with type 2 diabetes, obesity, and early kidney disease. It found that weight-loss surgery improved kidney function more than standard medical care in these patients.

Patients with type 2 diabetes (T2D) are at increased risk of chronic kidney disease (CKD). Some diabetes medications, such as those that mimic the GLP1 hormone, can reduce the risk of CKD. However, kidney disease remains an issue for patients with T2D despite standard medical treatment.

Obesity is also a risk factor for chronic kidney disease. Obesity is one of the causes of T2D, and T2D treatments including insulin can worsen obesity. Many patients have all three conditions.

Gastric bypass surgery is a treatment for obesity. Roux-en-Y gastric bypass involves surgically connecting the upper portion of the stomach directly to the intestines. The smaller stomach leads to feelings of fullness after eating a small amount of food. Additionally, food passes into the intestines faster. The intestines release hormones which decrease appetite. Gastric bypass leads to long-term weight loss, although like other major surgeries it can have complications. It is unclear whether gastric bypass improves kidney function for patients with obesity, T2D, and CKD.

This study included 100 patients with T2D. All patients had obesity meaning a body mass index (BMI) between 30 and 35 kg/m². All patients had CKD measured through the urinary albumin-to-creatinine ratio (uACR) over 30 mg/g. 51 patients were randomly assigned to receive Roux-en-Y gastric bypass surgery, and 49 received standard medical treatment. Medications were continued for both groups as needed, including metformin (Glucophage), insulin, and/or oral diabetes medications. Patients were followed for 24 months in this study.

Significantly more patients in the gastric bypass group achieved normal uACR by the end of 24 months (82% vs. 55%). Significantly more patients in the gastric bypass group reached a normal BMI (51% vs. 0%).

Glycated hemoglobin (HbA1c) is a measure of glucose control, and HbA1c below 6.0% indicates diabetes is in remission. More patients in the gastric bypass group achieved remission of their T2D (44.5% vs. 24.4%).

The same number of patients in each group (6) had a serious side effect. Side effects more common in the gastric bypass group included vitamin B12 deficiency, belly pain, and dumping syndrome (food entering the intestines too soon).

This study found that gastric bypass surgery improved kidney function in patients with T2D compared to standard treatment. It also found that gastric bypass surgery improved obesity and blood sugar control.

More patients in the gastric bypass group were of white ethnicity (90% vs 69%), which may influence health outcomes. This study was conducted in Brazil.