SAN DIEGO – Bariatric surgery induced a significant and durable improvement in diabetic nephropathy after 5 years of follow-up, results from a single-center study showed.
"In addition to significant weight loss, [bariatric surgery] achieves profound metabolic effects, including improvements in glycemic control and insulin sensitivity, as well as a decrease in cardiovascular disease risk and mortality," lead author Dr. Helen M. Heneghan said at the annual meeting of the American Society for Metabolic and Bariatric Surgery. "We hypothesized that improving diabetic control with bariatric surgery may have positive effects on the end-organ complications of this disease, such as diabetic nephropathy. We also wanted to address one of the prevailing questions in this field: whether or not the effects of bariatric surgery on diabetes and its complications are durable."
Dr. Helen M. Heneghan
Dr. Heneghan, a bariatric surgery fellow at the Cleveland Clinic Bariatric and Metabolic Institute, and her associates identified 52 patients who underwent bariatric surgery at the institute and had completed the 5-year follow-up. At baseline, the mean age of patients was 51 years, and 75% were women. Their preoperative mean body mass index was 49 kg/m2, 84% had hypertension, and 71% had hyperlipidemia. Preoperatively, the mean duration of diabetes was 8.6 years, and 29% were already taking insulin. Their mean hemoglobin A1c level was 7.7%, and 38% had diabetic nephropathy as indicated by microalbuminuria (30-299 mg of albumin per g of creatinine) or macroalbuminura (greater than 300 mg/g), and 22% of patients were prescribed an ACE inhibitor or angiotensin receptor blocker.
The majority of patients (69%) underwent gastric bypass; 25% had laparoscopic gastric banding and 6% had sleeve gastrectomy. Dr. Heneghan reported that 5 years after their surgery, 44% of patients had sustained remission of their type 2 diabetes, 33% had a significant improvement, and 23% had no change or worsening of their disease. This latter cohort "had the least amount of weight loss and were those who had the longest standing duration of diabetes preoperatively."
The rates of patients with remission, improvement, or change in hypertension were 16%, 50%, and 34%, respectively, whereas the rates for patients with dyslipidemia were 39%, 20%, and 41%.
Only 25% of patients who did not have diabetic nephropathy at the time of surgery went on to develop the condition. Among patients with preoperative microalbuminuria, 42% remained stable whereas 58% regressed and had no albuminuria 5 years after surgery. Similarly, among patients with preoperative macroalbuminuria, 50% remained stable and 50% regressed and had no albuminuria at 5 years.*
There were no preoperative differences in the mean urinary albumin to creatinine ratio (ACR) between patients who were and patients who were not prescribed a renoprotective agent. However, postoperatively, patients who were not on a renoprotective agent had a significantly lower urinary ACR, compared with those who remained on a renoprotective agent (P = .039). "This probably reflects the fact that patients who had improvement of their diabetes and regression or nonprogression of their nephropathy status also had a significant improvement in – or remission of – hypertension, and were no longer prescribed an antihypertensive medication," Dr. Heneghan explained.
She characterized the study’s overall findings as "remarkable, considering that diabetes is a chronic, progressive disease, and certainly warrant further investigation in the form of a prospective and larger study."
Dr. Heneghan said that she had no relevant financial conflicts to disclose.
*CORRECTION 8/28/12: The original sentence contained an error in describing the patients. The sentence should read" "Similarly, among patients with preoperative macroalbuminuria, 50% remained stable and 50% regressed and had no albuminuria at 5 years."