Operating on behaviour
The latest module in EASD e-Learning’s course on metabolic surgery launches today, written and presented by Dr Dimitri Pournaras, a prolific researcher in the field, who is also a bariatric and metabolic surgeon at North Bristol NHS Trust. And as his module shows, there’s more to this surgery than meets the eye…
Dimitri’s module is the perfect companion piece to the first module in this course, giving a surgeon’s perspective on the topic. But although Dimitri painstakingly covers all the different bariatric surgical procedures currently available, it’s a lot more than that.
The anatomy involved in these operations is complex. But the point behind them, at least as Dimitri describes it, is simple. “What we are all trying to do as obesity surgeons, obesity physicians, primary care doctors – different members of the multidisciplinary team – is not to make people look thin. We are trying to ensure they live longer, with a better quality of life, doing more things with their loved ones.”
So how is that achieved by surgery? Dimitri sees these procedures as “operations that work on appetite. They work by a physiological rather than a mechanical model.”
Put simply, they act on the messaging between gut and the brain that tells us we are hungry – specifically, changing eating habits by enhancing the post-prandial response of satiety gut hormones such as PYY and GLP-1; in effect, it’s behavioural surgery. “If you want to be philosophical about this,” says Dimitri, “if we cannot change the obesogenic environment we live in, what we can do is to change the way we perceive it. And the way we perceive our environment is via our gastrointestinal tract.”
His investigations in this area are a classic inversion of the bench to bedside model of research. He was already involved in laparoscopic bariatric surgery when he first noticed the remarkable improvements in glycaemic control seen post-surgery among patients with type 2 diabetes. The observation led him to question how this came about, resulting eventually in a fertile series of research collaborations with his colleague Alan Osborne and Professor Carel Le Roux, author of our first module on metabolic surgery.
Dimitri is careful, though, to manage expectations of type 2 diabetes remissions. “One in four patients goes into remission but one in five recurs, so we cannot really say that we are saving people from diabetes.” But there’s more at stake than simple remission. “If you look at glycaemic control after surgery, going from 8.1% before gastric bypass to 6.2% after the surgery is a fantastic outcome. It’s likely to lead to good cardiovascular outcomes in the future. And we all know from some of the classic studies in the field of diabetes that even a year or two of good glycaemic control may have lasting legacy effects.”