A growing commercial trend of healthy people using continuous glucose monitors (CGMs) and severely restricting carbohydrates is facing strong criticism from medical experts, who say temporary blood sugar spikes are a normal physiological response.
Authors, podcasters and wellness influencers have promoted blood sugar tracking as a way to prevent hormonal imbalances, acne and mood swings. However, nutritionists and endocrinologists stress that sudden rises in blood glucose after meals are generally harmless in people with normal metabolism, reports BBC.
How blood sugar works
When sugary or carbohydrate-rich foods such as fruit, white bread and pasta are digested, they break down into glucose, which enters the bloodstream.
The pancreas responds by releasing insulin, which helps transport glucose into cells for energy. Blood sugar levels typically peak about an hour after eating and return to baseline within two hours.
High-intensity exercise can also temporarily raise blood glucose. According to Jennifer Sherr, a paediatric endocrinologist at Yale School of Medicine in Connecticut, United States, hormones such as adrenaline signal the liver to release fuel for working muscles.
In people with diabetes, the body either produces insufficient insulin or develops insulin resistance. This can leave blood sugar dangerously high after meals and requires careful management through diet, exercise, monitoring or medicines such as insulin and metformin.
Not every spike is harmful
Medical experts stress that brief glucose spikes in healthy people are generally not a cause for concern.
Adrian Brown, associate professor in nutrition and dietetics at University College London in the United Kingdom, said the biggest misconception is that every glucose spike is harmful.
Concern is warranted when blood glucose remains elevated for longer than expected, which may indicate underlying insulin resistance. Prolonged exposure to high blood sugar can eventually lead to prediabetes and type 2 diabetes, as well as long-term complications including nerve damage, eye damage, heart disease and stroke.
However, Nicola Guess, a dietician and senior research fellow at the University of Oxford in the UK, said there is insufficient evidence to prove that excessive blood glucose directly causes insulin resistance.
Instead, Guess explained that consuming excess calories causes the body to convert surplus energy into fat, with weight gain becoming the primary risk factor for type 2 diabetes.
Questions over commercial glucose monitors
CGMs are essential for managing diabetes, but their growing marketing to healthy people has come under scrutiny.
Research shows that people without diabetes maintain blood sugar levels within a healthy range 96 per cent of the time.
Experts warn that CGMs can overestimate blood sugar levels, distort perceptions of health and encourage harmful dietary changes. A review by Associate Professor Brown and colleagues found a lack of consistent, high-quality evidence that CGMs improve health outcomes among people without diabetes.
Sherr noted that emerging research is examining whether CGMs could help identify people at higher risk of developing type 2 diabetes, although more evidence is needed.
Experts recommend a balanced diet
Rather than eliminating essential food groups, health professionals recommend maintaining a balanced diet.
Guess cautioned that avoiding carbohydrates can backfire, causing blood sugar to rise higher than usual when a carbohydrate-rich meal is eventually consumed. It can also lead to the unnecessary avoidance of healthy foods.
Rapid drops in blood glucose after meals may also increase hunger and overall energy intake.
For a steadier energy supply and better appetite control, experts recommend balanced meals containing protein, fibre-rich plant foods and healthy fats. They also suggest eating protein and vegetables before carbohydrates.
Wholegrains and protein-based foods can help keep blood sugar steadier and maintain satiety for longer than simple carbohydrates such as white bread and white rice.
Associate Professor Brown added that individual responses to food vary significantly depending on factors including sleep, stress, physical activity and meal composition.
Ultimately, experts agree that reducing excess added sugar remains beneficial, but glucose-monitoring devices are unnecessary for the general public.
