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New Zealand study

New Zealand study shows benefits of bariatric surgery

Many of those who had type 2 diabetes before their bariatric surgery had their type 2 diabetes resolve after surgery

Obese patients with type 2 diabetes had good long-term results after weight loss surgery, according to a study in New Zealand. The findings support other studies that indicate weight loss surgery is an effective and durable treatment for obesity associated with type 2 diabetes.

Wellington Hospital endocrinologist, Dr Richard Carroll recruited 120 New Zealanders who had bariatric surgery at least five years ago to take part in the study as part of a Health Research Council of New Zealand (HRC) clinical research training fellowship. The HRC-funded study is one of the first to look at the long-term effects of bariatric surgery in obese patients.

Carroll and his supervisor, fellow Wellington endocrinologist Associate Professor Jeremy Krebs, collaborated with New Zealand bariatric surgeon, Professor Richard Stubbs, on the study. Their results show that patients lost on average 25 to 30 per cent body of their body weight following gastric bypass surgery, and maintained this weight loss over the mean follow up period of ten years.

Richard Carroll

“What generally happens with bariatric surgery is that people lose weight very rapidly, hitting their lowest weight at about 18 to 24 months. There might be a little weight regain after this initial period, but most people maintained most or all of this weight loss over the follow up period,” said Carroll.  “Any weight regain didn’t appear to relate to the length of follow up or whether people had surgery five years ago or 15 years ago, their weight appeared to be reasonably stable.”

Although there were extremes – some people lost a huge amount of weight and maintained that while others didn’t lose much weight – no one was heavier at the final follow up appointment than they were just before surgery despite all patients being at least five years older. This, says Dr Carroll, is in “complete contrast to what we see with non-surgical interventions where weight loss is usually modest, and where any significant weight loss is all too often followed by weight regain”.

In addition to keeping the weight off, many of those who had type 2 diabetes before their bariatric surgery had their type 2 diabetes resolve after surgery.

“Of those with type 2 diabetes before surgery, 25 per cent had normal glucose tolerance by the end of the study, while 47 percent had pre-diabetes” he added. “That means 72 per cent of people had improved from having type 2 diabetes. To put that into context, only 5 to 10 per cent of patients who receive traditional medical interventions might normalise their glucose tolerance in the most rigorous clinical trials, and less than that in the real-world setting.”

A large proportion of the 28 per cent of patients who still had type 2 diabetes at the end of the study also saw improvements. At the time of their surgery, more than 90 per cent of this group were on medications for their diabetes to lower glucose. However, by the time of the study follow up, only 42 per cent still needed to take these medications and only one person required insulin.

“Most of us agree that the majority of what we see early after bariatric surgery can be put down to restricting calories. However, there are some other features going on too, particularly in terms of how the body handles glucose, that are different from what we observe after non-surgical weight loss,” explained Carroll.

HRC Chief Executive, Professor Kath McPherson, said a number of diabetes and obesity societies around the world are now recommending bariatric surgery as an intervention. Because there are significant costs associated with this, it’s important to have long-term data to show that the health and economic benefits of these surgical procedures outweigh the initial expense.

“Obesity and diabetes cause significant health problems for many New Zealanders, and place a considerable strain on our health care system,” she said. “Obesity is a risk factor for diabetes, cardiovascular disease, musculoskeletal disorders, and some cancers. Complications from diabetes include increased risk of cardiovascular disease, nerve damage, and damage to our organs with kidney failure being a very severe consequence. Investing in research that finds ways to prevent and address what are frequently debilitating, disabling and devastating health issues is crucial if we want fewer New Zealanders to experience these health issues and have optimal health and wellbeing.”

In other findings, Carroll found that blood pressure and lipid levels were both significantly improved by gastric bypass, and again, these benefits were still evident many years after surgery. Levels of depression were significantly reduced, while quality of life indicators such as physical function, self-esteem, and work performance all improved markedly.

On the downside, the frequency of osteoarthritis was higher after bariatric surgery than before, something Carroll believes probably relates to the damage done to people’s joints from their previous obesity and not the surgery.

Also, 49 per cent of people had zinc deficiency at the study follow up, stressing the importance of good nutritional follow up after bariatric procedures. Carroll  and colleagues at the Endocrine, Diabetes, and Research Centre in Wellington Hospital, are currently studying how to best correct this deficiency.

“We have an incomplete understanding of all the mechanisms that underlie the rapid increase in obesity that we’ve seen in recent years”, he concluded. “As well as being a very effective treatment for those with established obesity and type 2 diabetes, bariatric surgery has the potential to clarify poorly understood physiological aspects of weight control. Research in this field may provide clues as to how we could prevent weight gain in the first place, or achieve better weight loss results without needing to turn to bariatric surgeons.”

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