They're being promoted by some as tools that can help you lose weight, cure fatigue and live a healthier life.
Some influencers say
continuous glucose monitors
(CGMs) can improve the lives of those who are completely healthy, including athletes, saying that measuring blood glucose levels provides important health insights.
CGMs are usually about the size of a coin and are worn on the body, often on the arm. They contain a sensor that inserts just below the skin and, through a transmitter, sends information on blood glucose levels to a separate device or app.
But the devices were originally designed for
people who have diabetes
and need to constantly monitor their blood glucose levels.
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Sharon has diabetes. She says this device is 'buying' her more yearsMany scientists say CGMs are pointless for people who don't have diabetes and some say they could even be harmful if they contribute to people cutting out healthy foods in their diet as a response to normal spikes in blood glucose levels.
The United Kingdom's National Health Service's national diabetes adviser, Partha Kar, said earlier this year there is no strong evidence that CGMs help people without the condition.
Using a wearable monitor to test for pre-diabetes?
In 2021 Tim Veron co-founded Vively, a company that sells CGMs and an app that processes the data from the monitor.
It has sold 20,000 CGMs to around 10,000 customers, with about half of those sales made in the past six months. The company says it's expecting to have 40,000 customers next year.
CGMs are usually about the size of a coin and are worn on the body, often on the arm. Source: AAP / Katie Collins/PA/Alamy
Vively's marketing doesn't mention diabetes.
Veron told SBS News he started the company out of a "personal frustration" and a desire to give access to the device to people who don't have diabetes.
"A few years ago I found out that I had pre-diabetes. I was like, 'Wow, pre-diabetes, not an incredibly serious disease', but obviously it's heading down that path towards type 2 diabetes. So anything that you can do to kind of prevent that from happening I thought was pretty powerful."
He said using a CGM for six months provided him with "valuable insights" that helped him change his diet and behaviours and ultimately put his "pre-diabetes into remission".
Veron said he wanted to make CGMs more accessible to "people like me with pre-diabetes or with other kinds of metabolic dysfunction". He said Australia is in a "metabolic crisis".
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Veron said: "Vively is a wellness app and as such is exempt from the TGA, similar to a Fitbit or Oura ring. However, we take an evidence-based approach to the development of the app and education provided".
He said the company would seek TGA approval "for specific healthcare applications in the future, based on strong internal research data".
Why monitor glucose?
Glucose monitoring has been promoted by popular health podcasters Peter Attia and Andrew Huberman.
It has also been given massive exposure by French biochemist Jessie Inchauspé, who, under the alias Glucose Goddess, promotes books, recipes and supplements designed to stabilise glucose levels.
In a recent YouTube video, she said though "there are a lot of upsides" to wearing a CGM, she "does not recommend everybody wear one" because they are a medical device intended for people with a medical condition, and also said that people don’t need the monitor to pay attention to what they’re eating and how they’re feeling.
Dr Michelle Woolhouse is an integrative GP and Vively's medical director. In a post on Vively's website she said: "By monitoring their glucose levels, CGMs for non-diabetics can help them make more informed decisions about their lifestyle to optimise their overall health. This can potentially avoid the development of pre-diabetes or diabetes."
Woolhouse also says CGM devices can help athletes or fitness enthusiasts fine-tune their performance "by understanding how their glucose levels fluctuate during their training and competitions".
But Greg Cox, a sports dietitian and associate professor at Bond University who published research on CGM's earlier this year, said evidence on whether the devices help athletes monitor their fuelling was "inconclusive".
"We haven't found they're particularly useful (and wouldn’t be part of the advice) we would provide an athlete to help them better fuel around exercise," Cox told SBS News.
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I used my super to pay for weight loss surgery. It changed my life but wasn't all for the betterGlucose levels spike and fall significantly in people who have diabetes, but much less so in people that don’t.
Cox said that the monitors didn't pick up enough of an unusual reading in the data when athletes changed their fuelling and amount of exercise and therefore "it's inconclusive" whether they can be used to pick up nutritional deficiencies in athletes.
He said in a healthy person they're even less useful in measuring a person's energy levels and can’t measure overall health.
"While you can see changes in your blood glucose, when you use a CGM in someone that's healthy, those changes are a normal response to what you might expect for someone that's healthy that doesn't otherwise have diabetes," he said.
"The fluctuations that you're seeing in glucose, that's a natural and normal response."
Cox said people should be viewing food as more than just glucose.
"Food provides more than just a fuel for the body, it provides an opportunity to interact with family and friends."
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Daniella is not thin enough to be considered anorexic. There are calls for that to changeAmy-Lee Bowler is a lecturer in nutrition and dietetics at the University of the Sunshine Coast who co-authored the research with Cox.
She said it's concerning that people would use CGMs as a weight-loss tool, as some Vively ambassadors report doing in social media videos.
Explaining how that works, Veron said: "By taking control of your glucose levels and minimising elevated glucose, you can actually lose weight … by making behavioural changes".
He said Vively doesn't work with many ambassadors and prefers to advertise through genuine customer testimonies.
Bowler said: "I definitely don't think it's a healthy way to be stimulating weight loss because I think you're at risk of obsessed with the data and then if you're seeing any spikes, you're reducing your intake even further, which can be detrimental to health and wellbeing and performance if you're someone that's active.
"I definitely wouldn't be promoting that, but I think it's probably just someone's jumping on the bandwagon of a tool that everyone wants to use."
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Thomas eats 2kg of meat each day and says he's never felt better. But experts are concernedSome doctors on social media have used the term "glucose rexia" to describe patients who have formed unhealthy habits around glucose monitoring, in a way that’s comparable to the disordered eating typified by anorexia nervosa.
Veron said he hasn’t seen any evidence of this happening to people who use Vively.
Vively recommends people initially only monitor their glucose for 14 days, which is how long each CGM lasts. That is unless it gets bumped or water damaged, which Cox said was a problem during his research with athletes — some were going through two monitors in an hour because they were bumped.
Should people who don’t have diabetes use CGMs?
CGMs are subsidised by the government for everyone who has type 1 diabetes, but not those who have type 2.
Type 1 diabetes is when a person's pancreas stops producing insulin, and they need to regularly inject it.
Type 2 diabetes is more common and occurs when the cells in the body become resistant to insulin so more is needed to keep blood glucose levels within a normal range. It can usually be controlled through medication, diet, exercise and close monitoring, although some people take insulin.
A review of 27 studies, published in the Diabetic Medicine journal in June, found "a lack of consistent and high-quality evidence to support the utility of CGMs for … the early detection of abnormal glucose".
Bowler said the devices were expensive but that there's not enough evidence currently that they’re helpful for people without diabetes.
This article provides general information and should not be considered medical advice. Readers are advised to consult with a qualified health professional.