What is gastric bypass surgery and how many people undergo it?
Gastric bypass surgery is a type of bariatric operation that results in weight loss and stimulates metabolic effects that treat diabetes and other cardiovascular risk factors such as diabetes, high cholesterol, and hypertension.
The surgery is performed laparoscopically and involves dividing the stomach into a small proximal pouch and connecting the jejunum to the pouch with a Roux-en-Y configuration. This results in restriction of food intake, hunger control and early satiety, and a variety of gut hormone effects that favourably affect satiety and insulin secretion.
About 200,000 bariatric surgeries are performed in the United States every year and over half of those are gastric bypass procedures.
Please can you give a brief introduction to your research on diabetes patients who undergo gastric bypass surgery?
The positive effects of gastric bypass surgery on type 2 diabetes have been known for decades. In the last several years, though, much attention has been given to the mechanisms of action that results in diabetes remission after gastric bypass.
Our group and others have studied these weight loss-independent (gut hormone) effects of gastric bypass and conducted clinical trials evaluating the effectiveness of gastric bypass as a treatment for diabetes.
The current study presented at Obesity Week evaluated diabetic patients who underwent gastric bypass surgery in our practice and had at least 5 years of follow-up (median f/u 6 years). Several risk prediction models were applied to this group of patients based on their preoperative and their long-term postop risk factors.
What prompted this research?
There is relatively little published data reporting the long-term effects of gastric bypass on diabetes and hard endpoints of micro- and macrovascular disease after surgery.
The Swedish Obese Subjects study has published long-term (>10 years) results showing reductions in cardiovascular events and mortality after bariatric surgery compared to a non-surgical cohort, but a relatively small percentage of those patients underwent gastric bypass.
There is a need for more long-term studies looking specifically at the mechanisms and end-organ effects of diabetes improvement after gastric bypass.
What were the main findings of your research?
This retrospective study analyzed data on 217 patients with type 2 diabetes who underwent bariatric surgery between 2004 and 2007 and had at least five years follow-up. The patients were divided into three groups: 162 patients underwent gastric bypass surgery, 32 had the gastric banding procedure done, and 23 underwent sleeve gastrectomy.
We used strict criteria to define glycemic control, including an HbA1c level of less than 6 percent to define remission, which is a more aggressive target than the American Diabetes Association’s (ADA) recommended HbA1c target of 7 percent for diabetes control.
At a median follow-up of six years, data show that diabetes remission occurred in 50 percent of patients after bariatric surgery. Specifically, 24 percent of patients sustained complete remission of their diabetes with a HbA1c of less than six percent without diabetes medications, and another 26 percent achieved partial remission; 34 percent of all patients improved their long-term diabetes control compared to presurgery status. As expected, the patients who received gastric bypass experienced the highest rates of weight loss and diabetic remission.
The study shows significant reductions in the number of diabetic medications used in the long-term follow-up. There was a 50 percent reduction in the number of patients requiring insulin therapy in the long term and a 10-fold increase in the number of patients requiring no medications. In addition, the data show patients significantly reduced their cardiovascular risk factors according to the Framingham Risk Score. Diabetic nephropathy, characterized by high protein levels in the urine, improved or stabilized as well.
Were you surprised by any of the results?
No, we expect reductions in cardiovascular disease when metabolic syndrome is treated. Gastric bypass results in improvements or remission of type 2 diabetes and control of all of the components of the metabolic syndrome in most patients. It’s therefore not surprising that by changing the trajectory of these chronic diseases, we are reducing the risk of micro- and macro-vascular disease.
What impact do you think this research will have?
Hopefully, these long-term results will increase awareness in the broader medical community that gastric bypass surgery has important and durable effects that generally outweigh the risks of the procedure.
We also hope that this will prompt more long-term studies looking specifically at hard endpoints of cardiovascular events, retinopathy, and nephropathy after bariatric surgery.
What do you think the future holds for gastric bypass surgery?
Gastric bypass is here to stay. It has been used as a bariatric procedure since the 1960’s and has proven to be durable. When performed by experienced surgeons, gastric bypass is as safe as many other commonly performed procedures such as cholecystectomy and hip replacement. There are certainly some long-term risks associated with bariatric surgery and these have to be discussed in detail with patients as they determine which procedure is best for them. Patient education and careful patient selection is very important to achieve good long term results after these procedures.
Despite its known benefits, though, we still have a lot to learn about the mechanism of action of this operation. Specifically, its effects on nutrient sensing, bile acid metabolism, gut hormone stimulation, and adipokine effects are all active areas of research.
What are your future research plans?
We plan to continue following this cohort of patients for another 5 years and will continue to evaluate the long-term results of our randomized controlled trials.
Where can readers find more information?
About Dr. Brethauer
Stacy Alan Brethauer, MD, is a Staff Physician in the Section of Laparoscopic and Bariatric Surgery at Cleveland Clinic and the Director of Bariatric Surgery at Fairview Hospital. He attended the University of Colorado, Boulder, Colo., from 1985 to 1989, where he studied journalism and mass communication.
He attended medical school at Uniformed Services University of Health Sciences-F. Edward Hebert School of Medicine, in Bethesda, MD and received his MD degree in 1993.
He completed general surgery residency at the Naval Medical Center in San Diego, CA in 2001 and remained on active duty until 2005.
He then completed a research fellowship and a clinical fellowship at the Cleveland Clinic and joined the staff in 2007. His clinical interests include bariatric surgery, laparoscopic surgery, gastrointestinal surgery, hernia repair and endoscopy.
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