Nobody doubts that the arrival of the sensors for continuous monitoring of glucose levels, also called CGM (continuous glucose monitoring), has been a turning point in the daily self-care of diabetic patients. The reason: … Until their staging, they were forced to prick their fingers several times each day to measure the sugar levels in their blood, and thus be able to keep them at bay with insulin injections.
These small sensors are placed under the skin through an automatic insertion device that attaches to the arm or abdomen. They monitor interstitial glucose levels continuously, every few minutes. That is, the sugar found in the liquid contained between the cells. To obtain access to the information, the devices have a transmitter that is responsible for receiving the sensor data and sending it to a receiver, which can even be the mobile phone itself.
But CGMs are currently at the center of controversy. The reason: Its use is skyrocketing among non-diabetics. Among other reasons because they believe that it contributes to losing weight, a fact that is raising eyebrows in the scientific community. In fact, ‘WebMed’ itself recalls: «These devices are among the most recent that have attracted attention. Approved by the FDA for use in diabetesmillions of consumers are jumping on the bandwagon of its use, with the support of ‘influencers’ on social networks, and promises of better sports performance, weight loss and metabolic health.
It is enough to mention the case of Justin Richard, a TikTok user with more than 876,000 followers, who publishes videos in which he tries different foods (cereals, peanut butter, chocolate milk or a vegan lasagna,…) and observes how they affect to their glucose levels. He is not diabetic, but he is convinced that this monitoring is useful for preventing blood glucose spikes, due to his family history with the pathology. However, criticism, such as those collected in an article in ‘JAMA’ magazine, has not been long in coming. The argument: In healthy people glucose fluctuations are small.
Zoe’s controversial diet
And now eyes are on many of the nutrition applications that promote its use, such as the one launched by the British ZOE that has mobilized part of the United Kingdom medical community. This argues against it that its use is “unnecessary for people without diabetes and could, in extreme cases, fuel eating disorders,” as reported by the BBC.
ZOE offers a program, starting at around 350 euros, which is widely advertised, including on social networks. Participants record their food intake and wear a CGM for two weeks to measure blood sugar levels after eating. In separate tests, your responses to fat, triglyceride levels, and your gut bacteria are also analyzed.
The algorithm was previously able to predict how people respond to sugar and fat across different foods in a large 2020 study led by one of the company’s founders, Tim Spector, professor of genetic epidemiology at King’s College London. The package Zoe’s welcome kit includes a stool collection kit, a finger stick blood test and a CGM. And participants are asked to take a blood sample before and after eating a muffin specifically designed by the startup to contain specific levels of fat, sugar and protein.
Fermín Milagro Yoldi, director of the Nutriomics and Biomarkers Line at the Nutrition Research Center (University of Navarra), clarifies: «The glycemic response of an individual does not only depend on the food and their genetics. Basically there are two other important factors, which present great variability from one day to the next: Those that affect the intestine (digestion, absorption, microbiota) as well as hormonal and circadian factors. For example, the state of stress, having slept more or less hours or with better or worse quality of sleep,… This means, and we have seen it on numerous occasions in studies, that the response of the same individual to the same food “It is not the same one day or another.”
Reductionist approach
The expert insists that, on the other hand, prioritizing the effects of foods on postprandial glucose levels, instead of focusing on their other effects, is too reductionist. «This fact leads to eliminating, because they increase it, the intake of certain foods that can be very beneficial for health (such as fruits, whole grains or legumes) due to their content of fibers, polyphenols and other bioactive plant compounds that do not contain anything. “They have to do with glucose levels,” he adds.
Also remember that this type of food is associated, in practically all nutrition studies carried out in the world, with better health and a lower risk of diseases and mortality. «So under no circumstances should they be limited to people with normal glycemic health. Finally, the only point in controlling glucose levels after eating food is in people who have difficulty controlling these levels in abnormal parameters. That is, those with prediabetes and diabetes,” emphasizes the expert.
And if we mention the use of CGM for diabetes prevention, the doctor from the University of Navarra could not be more blunt: «There is no evidence that associates the size of the glucose peaks after eating certain foods with the greater or lesser risk of the disease and much less with the prevention of the same. It does make sense if this study is carried out in people with prediabetes. And even more so in those who suffer from the pathology,” he emphasizes. This specialist recognizes, however, that “any tool that helps identify a person’s response to food is useful for precision nutrition. But in this case, like the ZOE diet, too much importance is given to blood glucose. “In people with good metabolic health it is not one of the most important factors.”
Given all this panorama, and given the difficulty for the average citizen to distinguish the ‘straw from the hay’ when it comes to personalized nutrition, it is important to know that this is what depends on the physical and metabolic characteristics (your weight, physical activity, pathologies such as diabetes, hypertension, hyperlipidemia,…), as well as physiological characteristics (gestation, growth,…). But, in addition, it is important to keep in mind that “precision nutrition adds to the previous one the use of markers obtained through omics technologies, which are what allow obtaining many data at the same time by applying sequencing technologies (genetics, microbiota, epigenetics, …), proteomics or metabolomics.
They are two levels of the same philosophy: that of adapting a person’s diet and lifestyle to their genetic, metabolic and physiological characteristics in order to prevent diseases or control the risks that a person presents. Level 2.0 is precision nutrition because it uses data obtained with cutting-edge technologies that allow us to better understand a person’s characteristics,” explains Dr. Milagro Yoldi.
The role of the microbiota
Regarding the analysis of intestinal bacteria as part of this new way of personalizing the diet proposed by apps like ZOE, the expert recalls: “In recent years, much progress has been made in the knowledge of the intestinal microbiome, its relationship with health and how it is It modulates from various foods and environmental factors such as physical exercise, sleep, stress or drugs. But there is still a long way to go to learn to know it well, even though there are quite a few studies that link it to diet data. This is due to the great variability between individuals, since the microbiota also depends on factors that have nothing to do with diet, such as where you were born and lived, if you live with other people, pets or in a rural environment, or the treatments with antibiotics or other drugs.
New uses
For his part, Dr. Cristóbal Morales, endocrinologist and researcher at the Vithas Hospital and the Virgen Macarena Hospital in Seville, member of the Spanish Society for the Study of Obesity (Seedo) and member of the Spanish Diabetes Society (SED) , states that, although glucose sensors were born with a first indication for diabetes, “there is evidence” that they are also “a nutrition education tool».
«In other countries they are marketed under another name for people without diabetes because it is a complement in nutritional training. They even use them elite athletes forplan your physical training. The first indication is diabetes, and we must ensure the supply in this population, but, like everything in medicine, we are exploring new uses,” he points out.
Their recommendation is that, if someone without diabetes is interested in using it, it has to be accompanied by the advice of a health professionaleither. «In consultations we can improve certain parameters and what is not measured is not improved. Since Covid, society has changed and is more concerned about healthy aging. They want to change habits. Measurement can improve them and early,” concludes the expert.