Bariatric Surgery Least Favoured Route to T2D Remission

Liam Davenport

April 29, 2021

Bariatric surgery may be the most effective method of achieving type 2 diabetes remission, but it is the least favoured, suggests the results of a debate in which experts weighed the pros and cons of the main approaches.

However, no matter whether patients opt for intentional weight loss, a low-carb diet or gastric bypass surgery, the experts agreed that more support for type 2 diabetes patients to achieve remission is key.

Prof Carel Le Roux/DUKPC

The "idea that we can create remission for type 2 diabetes with all our various options has really enthused the populace," said Professor Carel Le Roux, Department of Metabolic Medicine, Charing Cross Hospital, Imperial College London. "And so people are not only asking for diabetes treatment now, they should be asking and are starting to ask for diabetes remission treatment."

The debate was held at the Diabetes UK Professional Conference 2021 on April 20.

Normalising Life Expectancy

Prof Mike Lean/DUKPC

Opening the discussion, Professor Mike Lean, chair of human nutrition, University of Glasgow, spoke in favour of intentional weight loss.

Professor Lean said that, in individuals with type 2 diabetes who have a mean age of 64 years and a body mass index >25, a 15kg intentional weight loss may normalise life expectancy, and achieves remission in 83% of cases.

These results led him and Roy Taylor, Newcastle University, Newcastle upon Tyne, to launch the DiRECT study, in which type 2 diabetes patients were randomised via their general practice to usual diabetes care or a structured weight management programme.

This involved withdrawal of all anti-diabetic and anti-hypertensive medications, total diet replacement for approximately 3 months, followed by gradual food reintroduction, and weight loss maintenance to 24 months.

As reported by Medscape Medical News, this achieved, against a target of 20%, diabetes remission in 46% of patients versus 4% with usual care at 12 months, and 36% versus 3% at 24 months.

Prof Lean said that the decline in remission rates between 12 and 24 months "was entirely attributable to weight regain", adding that "we have a problem with long-term weight maintenance and that's a problem we are working on".

Improvements Across the Board

However, the DiRECT intervention was not only associated with a mean weight loss of around 8kg versus usual care. Patients also saw their HbA1c levels decrease, with fewer therefore on medication. In addition, there were reductions in blood pressure, cardiovascular disease risk and associated healthcare costs, while quality of life improved.

There is also data to suggest that type 2 diabetes remission was associated with loss of ectopic fat, and a return to normal pancreas morphology and beta-cell capacity.

Crucially, these findings have also been replicated to varying degrees in other studies of intentional weight loss, with remission rates in randomised controlled trials typically ranging from 11% to 61%.

Very Acceptable

Professor Lean said that, for him, "intentional weight loss brings multiple benefits and it reverses the disease process" underlying type 2 diabetes.

There are different modalities for achieving that, including the "self-help approach" of eating traditional foods or a low carb diet, "which may not be optimal...but many patients are able to achieve that".

He continued that "evidence-based diet programmes have a cost which is balanced against the costs of managing diabetes," in addition to which it has "minimal side effects...and is very acceptable," with only 10% of patients who "fall by the wayside".

"GLP-1 agonists can achieve this degree of weight loss," Professor Lean said, and "are also very acceptable" but have "a greater cost".

Costs are also increased with bariatric surgery. It has a "potent effect" on weight, with a "long duration, but then it has a lot of side effects, minor in some terminologies, but they persist for life", and it is "not reversible".

Remission Need Not Rely on Weight Loss

Dr Nicola Guess/DUKPC

Next, Dr Nicola Guess, dietitian and senior lecturer, University of Westminster, London, spoke on behalf of low-carb diets.

She explained that such diets are also high in protein, and can be ketogenic. Low carb can also involve energy restriction when it's achieved by restricting starches and sugars.

She continued that she agreed with "everything that Mike said, that weight loss and its maintenance are of course the key drivers of type 2 diabetes remission".

Dr Guess acknowledged that the greatest weight loss is achieved through bariatric surgery, but that a low-carb diet is "as good as, if not better, than most other food-based approaches for weight loss".

For her, the weight loss is the "easy part", and that can help us get type 2 diabetes remission. But the "key point...is we want people to stay in remission, and we have to accept that whatever route people take to achieving weight loss, inevitably there's going to be a plateau, and in lots of people there's going to be some weight regain".

However, the "great thing about a low-carb diet is...it doesn't just rely on weight loss and its maintenance," Dr Guess said.

Effects Aside From Weight Loss

One of these is return of the postprandial insulin response, which is "critical" for type 2 diabetes remission. This, she said, is achievable without caloric restriction and weight loss, but rather through the addition of protein.

"We know from lots of studies that amino acids are insulinogenic...even in longstanding type 2 diabetes," Dr Guess maintained, adding that a 5-week weight maintenance programme with a low-carb, high protein diet reduced fasting glucose and postprandial excursions, all "without weight loss".

Importantly, the effects continued out to 10 weeks, which is "hugely clinically relevant".

Minimising the Pathophysiological Processes

Dr Guess went on to say that, whatever the method of weight loss used, the pathological processes that lead to type 2 diabetes in the first place need to be minimised.

There is data to show, she said, that a low-carb, high protein diet lowers liver fat and "if you go low enough" with carbohydrates, endogenous glucose production is reduced. This process "keeps us alive" during fasting but becomes "exaggerated" in type 2 diabetes.

Moreover, a ketogenic low-carb diet lowers blood glucose and is associated with the reduction or elimination of diabetes medications, and a significant reduction in insulin units, compared with a high-carb diet.

Taken together, these findings suggest that a low-carb diet could "offer hope for people with type 2 diabetes of longer duration", Dr Guess said.

Sisyphean Task

Finally, Professor Le Roux gave the case for bariatric surgery.

He began by saying that, when patients come to the obesity clinic, they "tell us that we have been asking them" to endlessly repeat the Sisyphean task of "trying to eat less and move more".

However, he "would suggest that surgery is the best way to achieve diabetes remission," because it takes the "boulder away, it makes life naturally simpler and achievable for our patients".

He continued that "more than 13 randomised controlled trials comparing surgery against best medical treatment...show consistently that surgery has the best evidence that we have" for achieving weight loss, regardless of the technique used, and with the benefit demonstrated out to 10 years.

"We need to decide what we want to practise as clinicians."

Le Roux asked: "Do we want to practise eminence-based medicine, which is 'what do the experts tells us', or do we want to practise evidence-based medicine?”

Functional Improvements

He then argued that, although bariatric surgery is associated with type 2 diabetes remission rates of 25% at 10 years, that is "not good enough" and "we could do better" if we combine surgery with medicine, which has already been shown to improve outcomes than with either approach alone.

Nevertheless, surgery "significantly outperforms" dietary or medical approaches, "because we have a 30% weight loss that drives functional ability", with 90% of patients reporting improvements in daily activities.

Complications are also significantly reduced with surgery compared to best medical treatment, with data suggesting that there is a 14-fold difference in the relative risk of micro- and macrovascular complications.

Turning to very low-calorie diets, which are typically given before bariatric surgery, Prof Le Roux said that both approaches are equally effective in terms of improving insulin resistance.

"However, where the difference comes in is when we look at the postprandial glycaemia," with surgery having a greater effect than dietary restriction, independent of the weight loss effect.

Surgery Should Not Be Forgotten

Prof Le Roux concluded that surgery is "currently the best method" of achieving long-term type 2 diabetes remission, but combining surgery with lifestyle changes "is likely to be far superior to any other option on their own".

"And we would certainly suggest that we need more diet approaches...more medications, and we need more surgery, but the fear is...we're going to forget about surgery, and if we do so we will lose out on a very powerful tool that can help our patients in the long-term."
 

Intentional Weight Loss the Winner

Prof Barbara McGowan/DUKPC

Before and after the debate, Professor Barbara McGowan, consultant and honorary senior lecturer in diabetes and endocrinology, King's College London, who chaired the session, asked the audience to say what they thought was the best way to achieve type 2 diabetes remission.

Initially, 68% were in favour of intentional weight loss, 20% leaned towards a low carbohydrate diet, and 12% thought gastric bypass surgery was best.

Once the experts had presented their arguments, intentional weight loss was slightly less popular, with 59% favouring the approach, while 22% thought a low carbohydrate diet was best, and those in favour of gastric bypass surgery increased to 19%.

No funding declared.

Professor Lean declares relationships with Novo Nordisk, Lilly, Roche and Sanofi.

Professor Le Roux declares relationships with Consilient Health, Novo Nordisk, Johnson & Johnson, ONO Pharmaceuticals, Covidien, Fractyl, GI Dynamics, Roche, AstraZeneca, Lilly, Boehringer Ingelheim.

No other relevant financial relationships declared.

Diabetes UK Professional Conference 2021: Expert debate: What is the best way to achieve type 2 diabetes remission? Presented 21 April.

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