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Evidence Based

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Can You Boost Your Wellness With a Continuous Glucose Monitor?

Written by Dr. Ruscio on February 13, 2023

Written by Dr. Ruscio on February 13, 2023 — Reviewed by Hilary Watts

Wearable biofeedback technology can provide the information you need in real-time to help motivate you to make positive changes in your health.

• Continuous Glucose Monitoring System (CGM) Explained|
• Meaningful Data: Ideal Glucose Numbers|
• Blood Glucose Change During Exercise|
• What Affects Blood Glucose and How to Make Tweaks|
• Knowing Seems to be More than Half the Battle|

Imagine a world where you could find out exactly which foods and activities had the best and worst impacts on your energy levels and sense of well-being throughout the day. You might not eliminate every food that wasn’t optimal (after all, a lot of suboptimal foods are delicious!), but timing when you eat them, how often, and how much of them you eat could really have an impact on your quality of life, right?

The good news is that we already live in this world. We know that what we eat has a big impact on blood sugar, and that blood sugar levels can affect mood (ever been hangry?), ability to focus, and physical energy levels. And we already have the ability to measure blood glucose through lab testing, as well as standard home kits using a drop of blood. But a snapshot of your glucose levels at a point in time may not be quite enough in some cases, especially if you’re struggling with metabolic issues like prediabetes.

By monitoring at home using a continuous glucose monitor (CGM system), you can empower yourself with far more data. You can see your daily averages, when and for how long your blood sugar spikes, which types of foods have the greatest effects, and how things like exercise, sleep, and stress affect your numbers. Think of a continuous monitor reading as a “movie” versus a blood test as a single frame.

The information a person can gather using a continuous glucose monitor is beneficial and best known for things like diabetes care and potentially reversing prediabetes [1]. But it may also be beneficial as a prevention tool and a health optimization tool. You don’t have to have a chronic disease or be an elite athlete to be motivated to improve your health scores. Rather, most of us fall somewhere in the middle and would just like to feel a little bit better than we do at present—more energy and fewer dips throughout the day [2].

Let’s dig into the details of continuous glucose monitoring: how it works, the pros and cons of this wearable tech, the ideal numbers to shoot for, how to interpret changes during exercise, and the most effective tweaks to make to start feeling better.

Continuous Glucose Monitoring System (CGM) Explained

A continuous glucose monitor (CGM sensor) is a small wearable sensor (medical device) that you can wear on your body painlessly at home for easy and accurate blood glucose monitoring. You place it on either the back of the upper arm or abdomen, where a small transmitter inserted into the skin collects glucose levels from the interstitial fluid beneath the skin.

The idea is to wear it continuously so that real-time readings can be collected and charted every 15 minutes over the course of days and weeks. You can look at the data on your phone or smart device like an Apple watch to help you get a better understanding of how your daily habits affect your blood glucose levels.

CGMs can send alerts for hypoglycemia events, which can be especially helpful during sleep. Some CGMs can work with insulin delivery devices (insulin pumps) and prevent insulin delivery if blood sugar levels drop [1]. Using CGMs as a wellness tool is a relatively new idea, but it’s growing in popularity as preventive and personal medicine become more and more mainstream. In fact, I have tested one out myself and learned a lot in the process about how alcohol, exercise, and even drinking a glass of antioxidant juice on an empty stomach can affect glucose readings. I talked about this experience and learned a lot more about continuous glucose monitoring on my recent podcast episode with Kara Collier.

There are a variety of products available that can help you monitor your blood glucose continuously over different intervals of time (seven to 90 days), based on the brand and type of product. In fact, one option is actually implanted under the skin and stays active for 90 days [3, 4].

The Upsides to Continuous Glucose Monitors

For those who are medically required to check their blood glucose levels throughout the day, this type of technology makes life a lot easier—no more painful fingersticks or clumsy test strips to deal with. Whether you’re dealing with type 1 diabetes, type 2 diabetes, gestational diabetes, or even prediabetes, knowing your numbers is critical, and constant finger pricks after every meal are annoying, cumbersome, and a little bit painful.

Although a huge umbrella review found that CGMs were as good as any other blood sugar monitoring system for controlling blood sugar in all types of diabetics, several meta-analyses determined that CGMs were better than self-monitoring for improving blood sugar control in people with type 1 diabetes, gestational diabetes, and type 2 diabetes [5, 6, 7, 8, 9, 10]. 

CGMs (which automatically show your latest blood sugar levels) were also better than flash glucose monitoring devices (which are like CGMs, but the results only show up when you scan your receiving device over the sensor) at improving blood glucose control in type 2 diabetics [11].

In nondiabetic people, CGMs may be used to detect [12]:

• Abnormal blood sugar regulation to help prevent prediabetes
• Blood sugar responses to different foods to improve nutrition
• Blood sugar responses to physical activity, which may inform a healthy exercise plan
• How stress levels can affect blood sugar levels, which can help with self-awareness and improvements in stress responses
• Blood sugar levels and fluctuations that may help to optimize nutritional strategies before, during, and after exercise
• How your sleep patterns affect your blood sugar [13]

A small study found that healthy people generally did not mind wearing CGM devices and tracking their nutrition and exercise for a week. However, their motivation to wear the CGM was only moderate, possibly because they weren’t sure how to interpret the data it provided [14]. 

Whether you’re dealing with a chronic metabolic illness or are simply looking to maintain/optimize your health, the real-time data that devices like these provide will help pinpoint which types of diets or even specific foods work great for your particular body based on your blood sugar levels after you eat.

The Down Sides to Continuous Glucose Monitors

Unfortunately these devices are expensive if health insurance coverage isn’t available, and they do require a prescription from a healthcare provider [1, 15]. Depending on which brand you choose to go with, there are start-up costs (purchasing sensors, transmitters, and a reader if you don’t want to use your smartphone) that range from $130 to $400 with an annual cost of anywhere from just under $2k to around $6500 [3, 4]. That being said, the healthcare costs they might save in the long run could make up for the upfront expenditure [15].

Furthermore, if you’re not using a CGM to manage a chronic illness, you can likely use it for a shorter period of time—around three months—to get a solid understanding of how your body reacts to various foods and lifestyle inputs [2].

Another pitfall is the volume of data you will receive. Sometimes too much data can be overwhelming, so choosing a CGM that makes the data useful through charts and simple scoring that’s easy to understand is the way to go. It’s also important to remember that CGMs are one tool that can assist you on your wellness journey. Try not to be a slave to the data or obsess over the details. Perfectionism isn’t the goal. So try not to get too hung up or over-stress about the data.

Meaningful Data: Ideal Glucose Numbers

Your real-time blood glucose meter is only as good as what you actually do with the information it’s collecting. Your CGM will be recording a data point around every 15 minutes, so recording your meals in the accompanying app and understanding the relationship between your numbers and your food intake is key to making meaning out of the information.

Many factors can affect blood sugar levels, including:

• The composition, glycemic load, and timing of the food you eat [12]
• The type, duration, intensity, and timing of physical activity [12, 16]
• Stress levels [12, 16]
• Illness [16]
• Menstruation [16]
• Metabolic conditions, like the insulin sensitivity of your muscles [12]
• Sleep quality [13]
• Medications [16] 
• Alcohol consumption [16]

Having a CGM to give real-time visual information (essentially biofeedback) about your blood glucose levels may help you make better choices about your nutrition, exercise plans, stress management skills, metabolism, medications, and sleep [12]. 

The numbers you’ll want to be looking at include:

• Average glucose value over a 24-hour window: Ideal glucose range is 70-140 (those on keto digesting ketones and not displaying symptoms of hypoglycemia can go as low as 60).
• Standard deviation of glycemic variability: Variability is normal. Ideally, there are minor swings after eating carbohydrates that resolve quickly after the spike.

• After your meal: Maximum glucose level (140 or below, ideally). If you’re shooting above that by a lot, you might look at the foods you’re eating before that spike, both what the foods are and how much of them you’re eating.
• How quickly your levels return to your number before you started eating: You want your glucose levels to recover within 2-3 hours of eating.

Reactive Hypoglycemia

Reactive hypoglycemia (low blood sugar) is a deep dip that can happen (even in non-diabetics) after the spike when eating carbohydrates. Type 1 diabetics are particularly susceptible to hypoglycemia due to a poorly functioning pancreas. A study looking at a number of glucose monitoring systems found that overall, CGM users with type 1 diabetes had significantly lower HbA1c and fewer incidents of severe hypoglycemia than those who self-monitored [6].

If you are not diabetic and experience hypoglycemic symptoms like dizziness, shakiness, hanger, getting hungry again soon after eating, it could indicate that there was something in the meal eaten before this that was difficult for your body to process. Having the CGM alongside food tracking will tell you exactly what happened so that you can begin examining your diet for foods that cause your blood sugar to take a dive. Again, try not to go overboard with analyzing the data. Becoming overly invested in the data can lead to more stress than it’s worth if you forget to keep perspective.

Blood Glucose Changes During Exercise

Once you start monitoring your levels regularly, you might notice a glucose spike while you’re exercising strenuously, and a slight dip during moderate exercise. According to the American Diabetes Association, moderate exercise tends to bring blood sugar levels down while exercising [17]. However, intense aerobic exercise and weight lifting can cause blood sugar to rise a little until your muscles are exhausted [17, 18]. This rise during strenuous activity isn’t cause for alarm, so please don’t mistake these numbers as a sign that you’re doing something wrong at the gym.

You can think about these as a supply and demand equation: intense energy demand requires more glucose than what’s in your blood supply, leading your liver to release more glucose to fuel the workout. Your blood sugar stays higher until your insulin levels rise and bring it back down, which usually takes place within an hour [18]. Glucose readings can get as high as 180 to 200 for elite athletes doing super intense workouts such as CrossFit or very heavy lifting. One way to reduce that spike is to make sure you’re properly hydrated before and during the workout, as dehydration can lead to greater spikes in blood glucose during strenuous activity.

Steady-state AND intense exercise all improve overall health and glucose response, so don’t let these spikes deter you from working hard at the gym, especially if you’re strength training [18]. Lean muscle mass is a net-positive for insulin sensitivity. Research seems to show that a lot of this rise in glucose increases glucose uptake across multiple types of tissue (muscle, organ, fat, brain, blood cells, and nerves) without the usual rise in insulin. In other words, thanks to non-insulin-mediated glucose uptake, more types of tissues than just muscle and fat are taking up glucose during exercise, which helps to return blood sugar back to normal without needing a huge amount of insulin to bring it down [19].

What you eat and when you eat it also affects what your blood sugar does in response to exercise [12, 20, 21]. CGMs can help you tailor and time your diet to minimize blood sugar spikes before and after exercise (12, 20). If your goal is putting on muscle or recovering quickly, ingesting a big meal right after a workout spikes glucose and stimulates an insulin response. While there’s not a lot of research on this particular strategy, it’s a well-circulated trend among pro athletes and bodybuilders. A glucose spike within normal levels (below 140) is safe, so doing this likely won’t hurt and could actually help.

What Affects Blood Glucose and How to Make Tweaks to Improve Health Outcomes

Much like the vast majority of other biomarkers you would want to measure for health, blood sugar is affected by four main factors: diet, exercise, sleep, and stress (12, 13, 16). CGMs are easiest to interpret as they relate to specific diet and exercise inputs, but the other two lifestyle factors really can’t be ignored. Stress affects insulin production and, over time, can decrease insulin sensitivity. Stress and poor sleep can also affect gut function and microbial diversity, which can have a negative impact on how we digest carbohydrates.

Here are some quick diet tweaks and things to look out for to improve your glucose data:

• Include protein with every snack, and avoid drinking sugary beverages on their own.
• Eat whole, nutrient-dense foods and minimize processed foods with empty carbohydrates [12].
• Pay attention to the timing of your meals and how eating late affects you personally, as everyone is different [12].
• Consider adding protein shakes and antioxidants to supplement your diet.
• Notice how alcohol affects your glucose levels, not just the day you imbibe, but the whole next day [16].
• Notice the difference in your levels when you eat larger meals and the length of time it takes for your blood glucose levels to return to normal**.

**When we eat really large meals, high in both carbohydrates AND fat, we’ll often see a smaller spike but a much longer time to return to normal because it will take your body a long time to get back to pre-meal levels.

Noticing Stress

If you use your CGM as a biofeedback tool, you might notice your numbers during a particularly stressful day or situation and choose to stop and breathe or make a different choice. You may also be more motivated to track your sleep so that you have more data to compare against your CGM numbers [12].

Some researchers claim that having too much health data could lead to increased stress or a desire for perfection, but the little research that’s been done on this topic doesn’t bear fruit [22, 23, 24]. Rather, two observational studies showed just the opposite, citing that wearables appear to reduce psychological distress and improve mental and physical health.

Participants who wore wearables were more likely to exercise and more likely to have a positive perception of their health [25]. Overall, wearable activity trackers appeared to be a source of positive psychological benefit to users [26].

This isn’t to say that zero people experience anxiety due to the constant stream of data. It’s helpful to be aware of this as a possibility, especially if your personality tends to zero in on details to the point of obsession. Remembering that the data you’re collecting is meant to be a helpful tool and not a vice that dictates your every behavior is super important.

Knowing Seems to Be More Than Half the Battle

It seems that having access to the type of data that CGMs can provide is incredibly beneficial, beyond the sum of its parts. When you choose a system that helps you interpret the data, not only are you empowered to make changes, you’re also empowered to test out certain foods at various times and quantities. Furthermore, it seems that the act of wearing the technology itself has a positive impact on behavior and sense of well-being, beyond the actual numbers.

This technology is pretty expensive without the help of health insurance, so it’s a good idea to inquire with your provider to find out if you qualify for a benefit. We’d love to help you get started in your journey to healthy blood sugar levels. Reach out to become a client at our clinic.

The Ruscio Institute has developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.