ADA 2017: Type 1 highlights (part 3) – Emily Burns
This is the final part of our Type 1 ADA series (congrats if you’ve stuck with us!), and we’re covering complications – from controversial foot ulcer treatments to the REMOVAL trial.
Hyperbaric oxygen therapy: fact or fiction?
Hyperbaric oxygen therapy (HBOT) was developed in the 1930s as a treatment for decompression sickness. It involves sitting inside a chamber and breathing in higher levels of oxygen than usual at a higher than average pressure. HBOT has since been used to treat many conditions, although the evidence base (outside of decompression sickness) has long been questioned.
The room was packed to hear the two sides of the HBOT story, with Dr William Tettelbach arguing the ‘for’ corner, as a US clinician who prescribes the therapy to people with diabetes who have foot ulcers. He says that he sees the benefits of HBOT in his clinics and believes it’s a useful tool.
It’s worth noting that the reason we’re having this debate is because we’re at the ADA: HBOT is a reality in the United States (there are three HBOT treatment centres in San Diego alone). So it must work right?
Dr Tettelbach acknowledged that several papers have suggested that the therapy doesn’t work, but he argued that the ‘control’ used in HBOT trials works against it. In a HBOT trial, the researchers compare the effects of sitting in a HBOT chamber to the effects of sitting in the chamber without the higher air pressure. That way, the environment is the same for everyone and you can look specifically at the effects of the air pressure.
Seems to make sense. But Dr Tettelbach argues that the ‘control’ arm actually has benefit, because the ‘sham’ chamber has a higher air pressure than a normal environment. Not as high as the real HBOT, but higher nonetheless. He references a study that looked at the effects of HBOT on people with mild brain trauma. The team had three groups: a real HBOT chamber, a ‘sham’ chamber, and no chamber. When they looked at the results, there was no difference between the real and ‘sham’ chambers. But both chambers resulted in improved cognitive function, while no chamber had no effect.
Convinced? Professor Andrew Boulton certainly wasn’t. He reminded the crowd that there was a similar debate 10 years ago and not much has changed since then. Professor Boulton believes that HBOT is surrounded by a long history of quackery and low evidence, with the therapy stuck in a history of case reports.
In the UK, a Cochrane review established that many of the studies into HBOT and foot ulcers are too poor a quality to draw any conclusions. There was some suggestion that the therapy may result in faster ulcer healing and reduce amputation rates, but they highlighted that the results should be taken with caution.
A 2010 Swedish clinical trial suggested that HBOT may help heal wounds, but pointed out that it’s an expensive method. Professor Boulton argues that you’ll get more bang for your buck elsewhere.
Conclusion? I think Professor Boulton wins…
Move over CGM: continuous foot monitors are in town
In a separate session, Professor Boulton also discussed innovations in monitoring the development of foot ulcers. He pointed out that the tissue in the feet usually heats up before ulcers begin to form, so technologies are being developed to monitor the feet for signs of ulcer formation. ‘Smart socks’ could sense temperature rises and pressure points – although more data on their ability to prevent ulcers is needed.
REMOVAL: does metformin protect the heart?
Rates of heart disease are considerably higher in people with Type 1 diabetes compared to the general population. The landmark DCCT trial showed us that controlling blood glucose levels intensely could reduce the risk of cardiovascular disease, but as REMOVAL team member Professor Helen Colhoun pointed out, controlling HbA1c at DCCT levels “remains elusive” for many people with Type 1. We need other strategies.
So the REMOVAL trial (with results now published in the Lancet) set out to establish if three years of metformin therapy could reduce the risk of cardiovascular disease in people with Type 1 (specifically, those over the age of 40 at an increased risk). Metformin is known to reduce HbA1c levels and the UKPDS trial (in people with Type 2) showed that metformin could reduce the risk of cardiovascular disease.
The team measured the average thickness of the carotid (neck) artery (known as cIMT) by ultrasound. Thickening arteries are a sign of cardiovascular disease. Scientists aimed to recruit 500 people to the trial, with final results comparing 152 people taking metformin to 175 on a placebo drug.
At the end of the study, there was very small reduction in HbA1c in the group taking metformin, alongside a small reduction in insulin dose. The difference in the average carotid artery thickness wasn’t significant at the end of the trial. However, a measurement that takes the bumpiness and plaque build-up in the carotid artery into account, was significant.
Interestingly, REMOVAL showed that the benefits of metformin for blood glucose control are short-lived, so Professor John Petrie, the REMOVAL trial leader, believes that doctors may prescribe the drug less often for people with Type 1 as a result.
And that’s it for our Type 1 series! Type 2 ADA highlights will be up shortly as well.
A disclaimer that with so much happening over the course of the conference, I only got a chance to catch around 10 percent! You can check out #2017ADA on Twitter to see news stories and updates from elsewhere in the world too.