Metabolic Surgery:
As increasing numbers of people have chosen bariatric surgery, doctors have observed, and research has confirmed, that 83% of patients experience a complete remission of type 2 diabetes after gastric bypass surgery (the gold standard in weight loss procedures), even before weight loss occurs. This is enormously significant, given the devastating impact of diabetes on public health in the U.S., and increasingly, throughout the world. Endocrine surgeon-researchers at the Columbia University College of Physicians and Surgeons are working to understand the reasons behind this unexplained benefit. Among those undergoing laparoscopic banding procedures, type 2 diabetes resolves in about half of patients—also tremendously significant. What is especially striking is that the resolution of diabetes occurs almost immediately after surgery, and before significant weight loss. Many patients can stop taking their diabetes medications shortly after surgery.
While resolution of diabetes after weight loss surgery clearly benefits those who are eligible for surgery (people with body mass index greater than 35), a study underway at Columbia University Medical Center is the first in the United States to explore surgically treating type 2 diabetes in people who are not obese. Understanding how weight loss surgery improves diabetes may lead to new ways of improving blood glucose control and ultimately help researchers identify a cure for type 2 diabetes.
DIABETES AND WEIGHT LOSS SURGERY
Researchers believe that bypassing the upper part of the intestinal tract, the 'foregut,' through surgery may cause hormonal changes that lead to improvement in diabetes. We know that the gut is a major player in diabetes resolution, that there is a pathway of communication between beta cells (insulin producing cells in the pancreas), the hunger center in the brain, and adipose tissue.
The gastrointestinal tract is the largest and most active endocrine organ in the body, and produces more than 100 hormones. One theory holds that after gastric bypass surgery, nutrients are delivered more quickly to the 'hindgut,' or the lower portion of the intestinal tract, where certain hormones such as GLP1 are released. GLP1 acts on beta cells, which make insulin. Judith Korner, MD, PhD, Assistant Professor, Department of Medicine and Director, Weight Control Center, Columbia University Medical Center, explains that "Delivery of nutrients to the distal gut may help to stimulate hormones that regulate blood glucose. We are not sure whether the resolution of diabetes is caused by bypassing the foregut, or rapid delivery of nutrients to the distal gut, or both."
Incretins are hormones secreted by the gut after meals to help increase insulin secretion. In type 2 diabetics, incretins are either present in lower concentrations or they don't work well, explains Dr. Korner. After bypass surgery, there is a change in incretin secretion, as well as in other hormones related to appetite control and insulin sensitivity. "This may explain why gastric bypass is more effective than diet and exercise in helping people lose weight and controlling diabetes," she says. "When people lose weight by diet alone, a hormone secreted by the stomach (ghrelin) stimulates hunger, and ghrelin actually increases after losing weight through dieting. Over 90% of people regain their weight after a few years. After bypass surgery, however, ghrelin does not increase, so people do not experience increases in hunger. This helps people to keep their weight off."
THE DIABETES SURGERY STUDY
Dr. Korner is Principal Investigator at Columbia University Medical Center in the Global Randomized Prospective Study of Intensive Medical Management of type 2 Diabetes, with and without Gastric Bypass Surgery.
The study is a multicenter, randomized, controlled trial taking place at Columbia University Medical Center, the University of Minnesota, and the National Taiwan University. It will compare the effects of weight loss surgery (gastric bypass) and intensive medical management with outcomes after medical management alone. The study will measure HgA1 levels (an indicator of blood glucose control) and risk factors for cardiovascular disease, such as LDL cholesterol and blood pressure. The study is enrolling people with type 2 diabetes who have a BMI between 30 and 34.9 kg/m2 (overweight but not clinically obese). Participants in the study are provided with free care for two years for diabetes management as well as the cost of surgery.
The study purposely includes Asian diabetics because type 2 diabetes occurs at a low body weight among Asian populations, possibly due to genetic differences. Differences among ethnic populations, including Hispanics, Dominicans, and others, will also be studied within the trial.
Eligible participants must be between 35-67 years of age, have type 2 diabetes, have a BMI between 30-34.9 (40-75 pounds overweight) and be willing to be randomized to medical treatment or gastric bypass surgery with medical treatment for two years. Participants do not have to be patients at Columbia University Medical Center.
If you are interested in learning about participation in the diabetes surgery study, please contact the study coordinator at dssresearch@columbia.edu.