Glucose (sugar) is an important source of energy for your body that can come from the food you eat or be made by your body, traveling through the blood (blood glucose) to bring fuel to your cells. Maintaining optimal glucose levels is crucial for overall health and well-being. Consistently high or low blood sugar and dramatic ups and downs in blood sugar can lead to short-term symptoms like fatigue, mood swings, and difficulty concentrating, and long-term issues like diabetes, cardiovascular disease, fatty liver, kidney damage, nerve damage, and eye problems. For people who have diabetes, tracking blood glucose and keeping the levels within optimal range are essential for preserving health. For people without diabetes, tracking and improving blood sugar levels can help detect and prevent health issues before they become more severe. It is estimated that more than 1 in 3 adults in the United States have prediabetes and only 12% of adults are metabolically healthy. Gaining a better understanding of our personal glucose levels and trends, and unique responses to food, movement, sleep, stress, and medication, can empower us to build healthier habits.
Using continuous glucose monitoring devices is growing in popularity by people with and without diabetes to support them in achieving nutrition and health goals. Continuous glucose monitors were first developed to help people with type 1 diabetes manage insulin dosage. However, over the past year, new biosensors (for those without diabetes or those with type 2 diabetes who are not taking insulin) have become available for purchase over the counter and directly from manufacturers without the need for a prescription. This new technology has been transforming the way we are able to visualize glucose patterns and make adjustments.
Gaining a better understanding of our personal glucose levels and trends, and unique responses to food, movement, sleep, stress, and medication, can empower us to build healthier habits.
A continuous glucose monitor, also known by its acronym “CGM,” is a small device worn on the back of the arm or abdomen that continuously tracks glucose in real time. The device (about the size of a quarter) has a tiny sensor less than 0.4 mm thick that is inserted just below the skin using an applicator, and adhesive tape holds the device in place. The sensor measures glucose in the interstitial fluid surrounding the cells below the skin and does not enter the blood vessels. Since CGMs measure glucose in the fluid between cells and not directly in the blood, readings typically lag behind blood glucose readings by 5-15 minutes. One CGM typically lasts 6-15 days (depending on the type), measuring glucose every few minutes, 24 hours a day. You can shower, swim, and carry on your daily activities while wearing the CGM. Depending on the type of CGM, glucose readings are either transmitted automatically to a smartphone or wearable device such as a watch, or transmitted after you scan the CGM using your smartphone or reader.
A traditional blood glucose meter requires a fingerstick and gives you a glucose reading at a specific point in time. On the other hand, a CGM gives you continuous glucose readings without the need for a fingerstick. Continuous, real-time glucose readings provide information about fluctuations in blood sugar levels throughout the day (glycemic variability), how often glucose is in the target or healthy range (time in range percentage), average glucose levels, and daily highs and lows and when they happen. You get immediate feedback about how the food you eat influences glucose levels and the quality of glucose spikes, including how high glucose rises after eating, and if and how quickly glucose returns to the pre-meal level. This information can increase your awareness about your body’s unique response to eating certain foods so that you can make lifestyle changes accordingly.
Different individuals can have different glucose responses to the same food or meal, so it’s important to understand your unique responses. For example, one person might experience a large rise in glucose after eating a slice of whole grain toast while another person might have a minimal response to eating the same thing. This can be due to differences in many factors such as digestive function, physical fitness, and the amount of muscle you have, which can impact how well insulin functions.
One person can also experience different glucose responses to the same food or meal when eaten at different times of the day, or in different contexts. Stress, poor sleep, and eating late night meals might contribute to elevated glucose levels. On the other hand, eating fiber and protein along with carbohydrates, and going for a walk after a meal might help lower the glucose response.
While a CGM might be a helpful tool for many people, it is not the right choice for everyone. Having so much data about glucose patterns can make some people anxious, can create an unhealthy fixation, and trigger disordered eating such as avoiding food when your body needs fuel because you don’t want to observe a glucose response. There is limited evidence about how CGM use benefits health in the long term. The cost of a CGM is high (about $50 for a CGM that lasts 2 weeks) and may not be covered by insurance. Keep in mind that a CGM is not a diagnostic tool and shouldn’t replace clinical support from healthcare providers. Fingersticks/blood glucose readings may still be needed in certain situations, such as when symptoms don’t match readings, if glucose rapidly changes, or if the CGM displays an error or signal loss.
Several brands and designs of CGMs are on the market, and the technology is rapidly evolving. Systems differ in their ability to sense extremely high or low values, send alerts for low or high glucose levels, and connect with insulin pumps. They also differ in the way information is transmitted and presented, and the length of time information is stored. Some types still require a prescription and are specified for people with diabetes. Dexcom and Abbott are leading manufacturers of CGMs, both offering multiple types. Stelo and Lingo are two popular biosensors used by people without diabetes. Companies such as Nutrisense and Levels offer dietitian support along with apps that help you interpret the data. If you want to try out a CGM, it is wise to have support from a healthcare provider who can advise you about whether a CGM is a good choice for you.
