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BOMSS 2013

Diabetic surgery put to debate at BOMSS

From left: Professor Mike Lean, Mr Torsten Olbers, and Professor Roy Taylor
Roy Taylor: incretin effect theory is "almost a belief system"
Mike Lean: diet and lifestyle intervention may provide more cost-effective outcomes in large populations
Torsten Olbers: sustained weight loss is the "magic" of bariatric surgery

A trio of clinicians gave three perspectives on bariatric surgery and its links to metabolic disease at the British Obesity and Metabolic Surgery Society’s annual meeting in Glasgow, Scotland, by turns challenging and defending bariatric surgeons’ belief that it is the most effective treatment for metabolic disorders.

In a wide-ranging discussion, Professor Mike Lean, the chair of human nutrition at the University of Glasgow; Roy Taylor, the director of the Newcastle Magnetic Resonance Centre and a specialist in the use of magnetic imaging in metabolic research; and Mr Torsten Olbers, a consultant bariatric surgeon and researcher for the Swedish Obese Subjects trial, spoke on subjects including the link between weight loss, liver fat, and diabetes; the outcomes that surgeons should be pursuing; and the evidence supporting surgery and medical interventions.

While all agreed that significant weight loss was the only effective measure to combat metabolic disease, the most cost-effective method of engendering weight loss was questioned.

Diet

“For a long time we’d heard about this reversal of diabetes [after bariatric surgery], and it all seemed to be very simple,” said Professor Roy Taylor. “The duodenum’s bypassed, so there’s a change in the incretins; this became almost a belief system around the world.”

However, he said, ascribing the sudden resolution of diabetic symptoms to the resection of the patient’s gastrointestinal tract ignores the “cataclysmic” effect that their sudden change in diet following an operation.

“To maintain a body weight of 152 kilos, day to day, keeping that weight steady, one would need to eat approximately 3,500 calories a day. As soon as one is nil by mouth for surgery, one goes from at least this figure to effectively zero, all of a sudden. It’s no surprise to me that their plasma glucose changed.”

To test this, he put a group of obese diabetics on a very low calorie diet, designed to give them 600 calories of energy a day. The results from the study showed that even after one week, fasting plasma glucose had normalised, and body scans showed that liver and pancreatic fat content had normalised to the level of a non-diabetic obese woman.

“This is a tedious diet, but that’s about as far as the bad news went,” said Taylor.

Lifestyle intervention

Professor Mike Lean also advocated the benefits of weight loss, suggesting that for a large number of obese people, 15kg of weight loss was a good target to see metabolic improvement.

“If you want to normalise it, a diabetic aged 60 has got to go up from a life expectancy of eight years; they have to have an increase of fifteen years,” said Lean. “Tall order, but that was correlated with a weight loss of 15 kilos.”

Using data from John Dixon’s 2008 study of  gastric banding, he said that for a patient weighing 100kg, a weight loss of 15kg would give them a reasonably good chance of achieving remission of type 2 diabetes.

“It’s not an absolute cutoff,” he said, “but it does show the sort of order of magnitude that allows me to say to my patients, you’ve got a good chance of becoming non-diabetic.”

It is clear that bariatric surgery can achieve this kind of weight loss, he said; however, as a physician he was interested in whether it was achievable in routine UK primary care.

Lean’s Counterweight Programme used a combination of a low-energy liquid diet and structured patient education. Solid food was gradually reintroduced to the diet until the patients had an estimated daily 500kcal dietary deficit.

Of the 91 patients who took part in the programme, 33% experienced a 15kg or greater weight loss at 12 months; 80% lost a similar amount after having a gastric band implanted.

Lean noted that the cost per patient who lost more than 15kg was £2,611; significantly lower than his estimated cost of £7,500 for a gastric band. Admitting that his analysis was “slightly tongue-in-cheek”, he said that for a million pounds, you could achieve 15kg weight loss in 100 patients using gastric banding, or 383 patients using his Counterweight Programme.

Surgery

Mr Torsten Olbers joked that after the first two talks, he was considering “giving up”, but still mounted a spirited defence of the value of surgery to treat metabolic disease.

“I entirely agree with the former speakers – [sustained weight loss] is the magic with bariatric surgery,” he said. “We have the treatment enabling long-term weight-loss maintenance. That’s what we can do.”

“We shouldn’t talk too much about the immediate effect; it’s long-term weight stability that is the magic with bariatric surgery.”

Despite affirming that weight loss is the cause of diabetes resolution after surgery, Olbers pointed at evidence that bariatric surgery was the only reliably effective treatment for diabetes and other comorbidities.

“With our best effort, with $250 million, we have tried with the best available efforts to treat patients,” said Olbers, “with weight loss, personal trainers and dieticians, and then you look at that outcome, and they stopped the study after 11 years, saying that there is no protection against cardiovascular events.”

In comparison, he presented data from the Swedish Obese Subjects study which showed a 30% reduction in mortality in surgical patients compared to the non-surgical control group.

Another study, by Mingrone and colleagues, compared bilipancreatic diversion and gastric bypass to medical therapy. “Not just any therapy – best medical therapy,” he said. At two years, 75% of patients who underwent gastric bypass had undergone remission from their diabetic symptoms, as had 95% of the biliopancreatic diversion patients; however, none of the medical therapy patients had done so.

“That’s a little bit about the reality,” said Olbers. “We can have occasional patients having a success story. But even if we have a strategy, we don’t reach very good results with medical therapy, unfortunately."

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