Monday, 25 July 2016
Study shows long-term benefits of weight loss surgery
Obese patients with type 2 diabetes in New Zealand have had good long-term results after weight loss surgery, according
to a new study.
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.
Dr Carroll and his supervisor, fellow Wellington endocrinologist Associate Professor Jeremy Krebs, collaborated with New
Zealand bariatric surgery pioneer 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 10 years.
“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. 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,” says
Dr Carroll.
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. 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,” says Dr Carroll.
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,” says Dr Carroll.
HRC Chief Executive Professor Kath McPherson says 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. 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,” says Professor McPherson.
In other findings, Dr 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 Dr Carroll
says likely relates to the damage done to people’s joints from their previous obesity and not the surgery. Also, 49 per
cent of people were deficient in zinc at the study follow up, stressing the importance of good nutritional follow up
after bariatric procedures. Dr Carroll, Associate Professor Krebs, 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. 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,” says Dr Carroll.
ends