While bariatric surgery may achieve remarkable levels of remission of diabetes, enthusiasm for the procedure should be tempered by a few caveats, according to Dr John Wentworth, an endocrinologist at Monash University.

Speaking at a session at ADC 2018, Dr Wentworth said gastric bypass was now the most common bariatric procedure used in Australia and typically resulted in a durable 30% loss of body weight.

However, while the procedure achieved good results in glucose lowering after two to five years, longer term data to ten years and beyond was still sparse.

In one landmark study, about 70% of patients were in remission from diabetes (HbA1c <6.5% and off therapy) at two years, but only 30% remained in remission at five years, he noted.

Dr Wentworth said the impact on patients’ quality of life and sense of wellbeing was “phenomenal” and should not be underestimated, but there was also a need to ensure that patients did not give up on other medications for lipids and blood pressure.

He also pointed to the fact that the impressive results were obtained from carefully selected and motivated patients enrolled in clinical trials, by surgeons who were highly skilled and experienced. The same results may not be achieved in real world practice and it was important to be careful in selecting both patient and surgeon.

Likewise, the randomised controlled trials of bariatric surgery had been done before the era of widespread use of SGLT2 inhibitors and GLP-1 agonists, whose benefits might alter the balance of risk reduction between medical and surgical approaches, said Dr Wentworth.

“The SGLT2 inhibitors are so cheap you probably have a duty of care to make sure they don’t work in your patient before you send them on for surgery,” he added.

The lack of long term data also applied to the important outcomes of complications for diabetes patients. Long term follow up studies showed that benefits in terms of reducing microvascular complications did not become apparent until at least five years after bariatric surgery, while reductions in macrovascular complications took even longer to become evident.

Patients with a shorter duration of diabetes seemed to show more rapid reduction in complications, he noted, which made sense because it would take longer to reverse the impact of lengthy glycaemic burden.

Dr Wentworth concluded by saying that bariatric surgery should be offered only to patients who were motivated to lose weight, and to patients who were aware of the small but significant risks of surgery and had no contraindications.

Cost of the procedure was also still a barrier and it was important to get data to take to the government to show it is good value for subsidy.

“I think the [Australian Bariatric Surgery] registry will help us work out what’s happening in the real world. The cost effectiveness question really needs to be sorted out and soon because I think it is really going to help us work out who those patients are who will get a return on the investment in a relatively short period of time,” he said.