Keeping tabs on blood sugar throughout the day used to be the exclusive domain of people with diabetes. But in 2026, anyone can buy a user-friendly wearable device that provides minute-by-minute readouts on how their glucose levels respond to food and movement.
These glucose numbers are increasingly being tracked by people who are healthy, but want to lose weight or optimize their wellness.
I am a behavioral scientist who has spent the past decade studying how real-time data captured through wearable sensors and mobile technologies can help promote a healthier lifestyle. I’ve found that for people who don’t have diabetes, using such a device for a few weeks can bring insight into how their body reacts to their eating patterns and daily habits.
But researchers still don’t know how these fluctuations affect people who don’t have diabetes. In the absence of a meaningful way to interpret these numbers, monitoring a constant stream of data doesn’t directly help people make health-related decisions and can lead to confusion and needless anxiety.
What are glucose levels – and why track them?
Glucose is a type of sugar that circulates in the bloodstream after being absorbed from food. It is the body’s primary source of energy.
For people without diabetes, glucose levels generally stay in the range of 70-120 milligrams per deciliter (mg/dL) of blood throughout the day. After eating or drinking, levels could exceed 140 mg/dL but should return to normal within a couple hours. That’s because the pancreas responds to a glucose spike by releasing a hormone called insulin, which brings glucose down.
Muscles burn glucose for fuel, so physical activity also helps normalize glucose levels.
Glucose levels generally run high with diabetes. People with Type 1 diabetes, whose bodies don’t make enough insulin, rely on glucose numbers to tell them when to take a dose of insulin. People with Type 2 diabetes use the numbers to monitor the effect of their medications and lifestyle changes and to get a fuller picture of their glucose control.
From test strips to AI-enabled sensors
Devices that track glucose numbers have been around since the early 1970s. Early versions consisted of test strips that detected glucose levels in urine. Finger prick tests, or glucometers, were developed in the 1980s and are still in use today. They measure glucose levels through a tiny blood drop to a test strip.
To make the technology more convenient, companies in the early 2000s developed continuous monitoring devices that consist of tiny sensors inserted just under the skin that detect glucose in fluid that surrounds cells. At the outset, these devices could give readings every five 15 minutes for several days at a time.
Today, the technology has evolved even further. The most advanced glucose monitors come in the form of watches or rings with noninvasive sensors that use light-based techniques to detect glucose in body fluids. Many also rely on machine learning to provide more accurate readings by detecting each person’s unique physiological patterns over time.
For decades, continuous glucose monitors were available only with a doctor’s prescription. But in March 2024, the Food and Drug Administration approved the first over-the-counter continuous glucose monitor in the United States, making them widely accessible.
Glucose monitoring for diabetes
There’s no doubt that continuous glucose monitors are a game-changer. People living with diabetes rely on the devices to track what percentage of the day their blood glucose stays within healthy limits — a measure called “time in range.” Patients make decisions about managing their condition — for example, when to take insulin — on guidelines developed by researchers and physicians.
According to a recent 2026 report from the Centers for Disease Control and Prevention, almost 11 million adults who have diabetes — more than 1 in 4 adults with the condition — are undiagnosed. Type 2 diabetes can develop slowly and silently, often with no noticeable symptoms for years except glucose levels that remain elevated for extended periods of time.
Tracking glucose levels may also benefit the 115.2 million Americans — nearly 44 percent of all adults — who have a condition called prediabetes. Prediabetes is when a person’s metabolic system shows early warning signs, but they don’t have the full-blown disease.
Prediabetes generally has no noticeable symptoms, but it is reversible — meaning, it’s possible to shift your glucose levels back into a healthy range. Tracking your glucose number can reveal how diet and exercise affect it: Seeing how a soda spikes your glucose levels, might give you pause before you drink one next time.
Daily glucose rhythms
Increasingly, though, people who use continuous glucose monitor aren’t diabetic — or even prediabetic. Instead, many now want to understand how their bodies react to activities in their daily lives.
Diet, exercise and other lifestyle behaviors have long-term health impacts. Weight loss, for example, happens slowly. Changes in blood glucose, on the other hand, are more immediate. Tracking glucose levels offers real-time feedback on how your body responds to food or a workout.
In studies I’ve conducted with colleagues, many people have found this information powerful. They were surprised to learn that eating certain foods — sugary soda, or even something healthy like a banana — causes their glucose levels to spike.
One study participant said seeing their real-time glucose numbers led them to make more intentional dietary choices, such as cutting back on snacking. “I’m more aware and I’m making the changes,” this person explained. Another participant also reported making changes after continuous glucose monitoring, trying to avoid eating so late in the evening and consuming only half a fast-food meal.
That initial wow factor — and its capacity to motivate people to make healthy lifestyle changes — may be valuable. But it’s not clear how long these changes last, or how exactly people should respond to fluctuations in their glucose number to decrease their diabetes risk or to address other health issues.
Unlike the time in range guidelines for diabetes, there is no clear framework for what daily glucose patterns are abnormal in people who don’t have diabetes — or what patterns may indicate future risks.
Currently, the user interface from continuous glucose monitors is designed for individuals with diabetes. For example, warning signs will show up if the glucose is “too high” and alarms will set off if the glucose number is “too low.”
For people without diabetes, these warnings won’t always apply. A single glucose reading of 180 mg/dL does not mean you have diabetes. But seeing the warnings from the glucose monitor app may bring stress and confusion.
In addition, the cost of an over-the-counter continuous glucose monitor is about $150 without insurance for 14 days of monitoring. Without insurance coverage and clear guidelines for individuals without diabetes, the public health benefit is questionable.
Mapping the numbers
Researchers like me and my team are exploring exactly these questions.
Building a dynamic picture of how glucose levels fluctuate throughout the day in people without diabetes may point to early indicators for some chronic diseases. For example, my colleague and I recently developed a mathematical model to examine how monitoring glucose levels during sleep might help predict the risk of metabolic diseases — such as Type 2 diabetes, heart disease or fatty liver disease — in people.
We are launching a study this fall to further develop this model to include data from other commercially available sensors, such as heart rate and blood pressure, and apply it to real-life monitoring.
We will see if our model is able to capture the day-to-day variations in these data and translate them into easy-to-understand risk scores that can guide changes in daily behaviors.
Continuous glucose data may reveal how people’s bodies might react differently to the same food, workout or other physical activity. Understanding how each person’s biology responds to the choices they make throughout the day could eventually lead to a more personalized approach to lifestyle changes to help people maintain their health.
Liao Yue, PhD, is an Assistant Professor of Kinesiology at the University of Texas at Arlington.
This article was produced in collaboration with The Conversation, a nonprofit news organization.
The post I study wearable health data. Here’s what continuous glucose monitors miss. appeared first on Washington Post.
