Using blood glucose meters to track diet ‘may cause anxiety’

The use of blood glucose meters in people without diabetes is not supported by research and could cause anxiety, experts warn.

The monitors are widely advertised as a way to personalize diets and are marketed by several companies, including as part of Professor Tim Spector’s Zoe programme.

Zoe says on her website that blood sugar spikes can lead to an increased risk of heart disease over time.

The program assesses a person’s blood sugar responses to food and also looks at blood fat levels and gut bacteria.

“Based on this information, we can provide personalized nutritional advice to help you minimize blood sugar spikes and achieve your long-term health goals,” it says.

However, several experts have questioned the research evidence behind Zoe, along with other programs using continuous glucose monitors for people without diabetes.

The monitors are often used by people with diabetes who rely on insulin pumps to ensure that their blood sugar levels remain stable.

In the new review, researchers from University College London and Birmingham Children’s Hospital concluded that there is a lack of evidence to support the use of CGMs in people without diabetes.

They said the devices can also cause people anxiety and lead them to restrict certain foods, such as in orthorexia, an obsession with “pure foods”, and argued that “spikes” in blood sugar levels after eating are completely normal.

Senior study author and dietitian Dr. Adrian Brown, from UCL’s medical department, told the PA news agency: “Our research found that there was a lack of consistent and high-quality evidence to demonstrate the effective use of continuous glucose monitors in people. not living with diabetes.

“Right now, CGMs can be sold by companies, but they have no medical use.

“We have good evidence that they have changed the lives of people with type 1 diabetes, and to good effect for people with type 2 diabetes on insulin therapy.

“But for people who don’t have diabetes, we don’t have the same data.”

Dr. Brown said that when companies promote “personalized nutrition to help people adjust their diet and keep their blood glucose within normal limits, the data is questioned and incomplete.”

He added: “We’re not saying that CGMs may not have a benefit. However, currently there is still limited evidence to support commercial companies’ claims about the use of CGMs in people not living with diabetes.”

He added: “What constitutes a normal blood glucose level varies from person to person, it varies within the same person at different times of the day.

“And the accuracy of CGM varies depending on the CGM model used.

“Even with good CGMs, there is still about a 20% variation in accuracy in the blood glucose displayed.

“Someone who does not have diabetes has a normal blood glucose level of between 3.8 and 7.8.

“However, the monitor could display a value between 2.6 and 9.4, indicating a potentially low or high blood glucose, despite (the person) having normal blood glucose.

“This may affect people who see results that are in fact normal blood glucose readings and adjust their diet accordingly.”

Dr. Brown said people without diabetes will experience brief periods of elevated blood glucose after meals, but – because they generally have good blood glucose control anyway – these often return to normal within one to two hours.

And while people with diabetes can have long periods of elevated blood glucose, which can jeopardize their long-term health, the shorter-term spikes after meals have not currently been linked to poor long-term health outcomes. he says. said.

He added: “I think there must be evidence behind some of the advertising from CGM companies, related to the evidence currently available.

“There are a lot of anecdotal benefits reported by people who may have used companies.

“What is important, however, is that companies stick to what the published data says.”

Dr. Brown also said better regulation of the devices is needed.

“The review found that in people who do not have diabetes and use CGMs, this could potentially cause anxiety about what normal blood glucose is and also how this affects their diet,” he said.

“So there is a potential risk for the development of eating disorders such as orthorexia – an unhealthy obsession with eating ‘clean’ foods.

“So, for example, there may be foods that they consume that raise their blood glucose higher than they want, and there is a possibility that people end up avoiding healthy foods that ‘raise their blood glucose’ but are healthy by national standards. dietary guidelines, based on the idea that these spikes in blood glucose are actually negative, as opposed to a normal response to eating high-carbohydrate foods.”

Dr. Brown called for more independent research into CGMs, adding that the majority of personalized nutrition data comes from industry-funded research.

“Particularly around CGMs, the vast majority of data, even from people with diabetes, is industry funded… So there is a need for more independent research to be conducted outside of commercially funded research,” he said.

CGMs are designed for people with diabetes and work by monitoring blood glucose levels in real time.

In people with type 1 diabetes, measurements can be taken from an insulin pump, which delivers the right amount of insulin needed to keep blood sugar levels stable, and can be useful for people with type 2 diabetes.

The new study, published in Diabetic Medicine, included a review of 25 existing studies and warned that CGMs “are gaining popularity among people not living with diabetes.”

The researchers said: “We argue that there is an inadequacy of regulations that encourage off-label distribution of CGM and call for strengthening post-marketing clinical follow-up surveillance.

“We hope this will help prevent the ongoing risk of misinformation for people not living with diabetes, and the ‘off-label’ worsening of health disparities.”

Zoe has been contacted for comment.

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