It seems obvious that cutting away part of the stomach and intestine should cause weight loss. With a smaller stomach and less intestine fewer calories can be absorbed per day causing weight loss. Surgeons who perform gastric by-pass were puzzled however, by how fast their patients showed metabolic improvement after undergoing this procedure. They noticed many of their diabetic patients could be taken off diabetic medication immediately after surgery before weight had been lost. Scientists looking into this phenomena discovered unsuspected ways gastric by-pass improved metabolism.
The intestines produce hormones which regulate blood sugar and appetite. GLP-1 is among the best known of these intestinal hormones. GLP-1 is the basis of a whole new generation of medications used to treat diabetes such as Byetta, Victoza, Januvia and Onglyza. GLP-1 lowers blood sugar, stimulates the pancreas and reduces appetite. After gastric by-pass increased amounts of GLP-1 are produced by the remaining intestine. In a study published in the Journal of Clinical Endocrinology and Metabolism (95:4072-4076, 2010), researchers at St. Luke’s Hospital in New York discovered that levels of oxyntomodulin, another intestinal hormone that suppresses appetite and acts like GLP-1 on blood sugar levels, is doubled after gastric by-pass.
These exciting discoveries help explain why obese diabetics can often be sent home without any medication to control blood sugar immediately after undergoing gastric by-pass surgery. Although most insurance plans do not cover gastric by-pass surgery, dramatic improvements in patients after the procedure with greatly reduced medication costs may convince insurance companies that paying for the procedure will result in better outcomes and save them money in the long run.
Gary Pepper, M.D.