CGMs: Pathologizing normal responses or protecting future health?

CGMs are well-established devices frequently prescribed by doctors to those suffering from diabetes to enable patients to closely monitor and manage glucose levels. Their use by healthy individuals has also exploded in recent months as they become more widely available through companies such as ZOE.

In addition, the topic of blood glucose management has been widely discussed and recommended online by influencers such as Steven Bartlett and the Glucose Goddess.

However, there have been growing concerns that the everyday use of CGMs and the ‘gamifying’ of blood sugar monitoring may lead to more harm than good in those without metabolic conditions.

While nutritionists have argued that they risk pathologizing normal blood sugar responses and may create unhealthy eating behaviors, experts from industry have argued that CGMs may provide a preventative tool against future metabolic conditions​.

Normal vs. abnormal glucose response​

Clemence Cleave, nutritionist and founder of Rocket Fuel Nutrition, explained that normal blood glucose levels typically fluctuate between 3.9 and 7.8 mmol/L.

“But it isn’t unusual to experience higher glucose spikes from time to time due to factors such as the time of the day, level of fatigue, and type of food eaten,” she noted. “These higher spikes would still be considered normal responses.

“However, if a person experiences spikes above 10 mmol/L on a regular basis, while eating a fairly balanced diet, this may indicate an abnormal response.” 

She stressed that while lifestyle modifications may help flatten these spikes, they might be symptomatic of an underlying condition and need further medical investigation.

Andy Franklyn Miller, chief medical and innovation officer at Nuritas, emphasized that frequent spikes from excess glucose may cause systemic inflammation, which is observed in pre-diabetics and those with metabolic syndrome.

“There is a need for more evidence around the area of inflammation, long-term health and blood glucose, but certainly there are significant bodies of work already highlighting the need for this to be a significant area of health focus and prevention,” he said.

Personalized nutrition company ZOE has also spotlighted existing research suggesting that frequent blood sugar spikes may be linked to long-term health issues​ in healthy individuals. The company provides CGMs as part of its personalized nutrition program.

In a statement shared with NutraIngredients, ZOE highlighted its efforts to inform customers of the science behind blood glucose levels.

"ZOE members wear the Continuous Glucose Monitor (CGM) for two weeks, which is just one part of its clinically designed program," it read. "During this time, members receive lessons explaining how blood sugar rises are normal and healthy. Data from the CGM, stool sample and blood fat are then analyzed to generate personalized dietary advice.

"We don’t believe wearing a CGM is necessary over the long term for people without diabetes, however, it is useful as one of the metrics to create the personalized food scores found in the ZOE app."

Do we really need CGMs?​

"People do not need CGM to be healthy or to even know what to feed themselves," Cleave said. "Over the past few months, people have been fed with a narrative that they need to control their glucose spikes as much as possible. There is an element of truth to this: a diet rich in refined sugar would lead to lots of glucose spikes and could be damaging for health."

Yet she argued that CGMs are not required in order for consumers to be informed of the risks associated with excessive sugar intakes, and said such devices may only be necessary for those with gestational diabetes, type 1 or type 2 diabetes.

"There is no need to micromanage each glucose response from your body," Cleave added. "One of the main concerns with CGM use it the potential for pathologizing something normal, causing unnecessary worry and dietary restrictions.

"Plus, focusing solely on glucose responses may distract us from the bigger picture of a healthy diet. People may start avoiding nutritious foods like fruits or grains in fear of spike their glucose, preferring glucose-stabilizing foods like processed meat and butter. We certainly don’t want that!"

Claire Baseley, registered nutritionist and regulatory expert, agreed and emphasized that the devices may cause further health issues.

"CGMs risk causing a disordered relationship with food where carbohydrates, including fruit, are demonized and individuals may start eliminating perfectly healthy foods from their diet, owing to their short-term effect on blood sugars," she said.

"They should be used with extreme caution in healthy individuals. Information should be provided to explain that blood glucose rises are normal and no cause for concern, and individuals should be encouraged not to eliminate healthful foods like fruit and whole grains but instead should reduce their intake of food and drink with high levels of free or added sugars, where relevant."

Miller agreed that long-term use of monitors should not be recommended but highlighted that glucose regulatory products and devices can offer a natural alternative to medication in the short-term and additional support in a world where foods high in glycemic index are often difficult to avoid.

"Also, the amount of education one can gain from seeing which carbohydrate heavy foods cause a glucose spike, which are very much on individual level, is significant," he said. "Two weeks with a wearable can give significant insight."