Diabetes can be a complex and challenging disease to manage due to the constant fluctuation of blood sugar as a result of lifestyle factors. The goal for most adults with diabetes is a hemoglobin A1c (a blood test that gives an average blood sugar over the last 3 months) of < 7.0 to reduce the risk of complications. However, studies have shown that the number of patients reaching that goal is 50% or less due to poor medication adherence and difficulty titrating medication to individual needs. There have been many innovations in glucose monitoring to enable patients with diabetes to improve their disease control. 

A relatively new technology known as continuous glucose monitoring (CGM) can provide real-time blood sugar readings, allowing for more precise monitoring and titration of medication. CGM is a valuable tool in functional medicine for diabetes care, as it allows for a more personalized approach to management.

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Understanding Diabetes and Its Management 

Diabetes mellitus is a metabolic disease resulting in elevated blood sugar levels, with multiple subtypes (the main ones being Type 1 and Type 2). When we eat food, stored energy is metabolized to be used as fuel for the body. Glucose (sugar) is one byproduct of this process and is released into the bloodstream. This signals the pancreas to release insulin, which allows cells to uptake glucose. In Type 1 diabetes, the body can’t make an appropriate amount of insulin resulting in insulin deficiency and persistent elevation in blood glucose. In Type 2 diabetes, the body cannot use insulin correctly, also resulting in persistent elevation of blood glucose, and accounting for 90-95% of all diabetes.

Differentiating between Type 1 and Type 2 diabetes is not always clear, but both subtypes can present with elevated blood sugar levels causing increased thirst and urination. Typically, T1DM symptoms develop rapidly, over weeks to months, while symptoms of T2DM often take years to develop. Other common symptoms of type 2 diabetes can include fatigue, vision changes, poor wound healing, frequent infections, hyperpigmentation of the skin around the neck and underarms, and numbness/tingling in the hands and feet, all due to elevated blood sugar levels.

An overview of diabetes management includes lifestyle changes and medication to keep blood sugar within a normal range. Medication can include oral pills (such as metformin, sulfonylureas, DPP-4 inhibitors, SGLT2 inhibitors, and one GLP1ra), or injections. Injections can include insulin and GLP1ra. Because the medications work in different ways to lower blood sugar levels, they can be combined as required to meet individualized management goals. Insulin, and some of the other medications, have the known side effect of hypoglycemia if not monitored regularly and adjusted. In addition, low-carbohydrate diets, which are commonly recommended for the management of T2DM, carry a risk of dropping the blood sugar too low, especially when combined with other medications. Regular blood glucose monitoring can allow safe and efficient management of diabetes. 

What is Continuous Glucose Monitoring (CGM)?

Continuous glucose monitoring (CGM) technology is a relatively recent innovation in diabetes with a significant impact on improving blood glucose control. Understanding CGM compared to traditional monitoring of blood sugar with a finger-prick glucose monitor highlights its key difference in providing both in-time blood glucose levels and an indication of whether the reading is trending up or down. Components of a CGM system include a subcutaneous sensor that frequently and regularly measures glucose levels in the fluid around the cells of the skin, a transmitter to send the readings, and a receiver to display the readings. There are two main types of personal CGM systems – real-time CGM, which automatically transmits data to the patient’s receiver, and intermittently scanned CGM, which requires the patient to manually swipe the receiver by the sensor to obtain the data. The FreeStyle Libre 2 CGM can use either a smartphone app or a handheld touchscreen device as a receiver. The Dexcom G7 CGM automatically sends a reading to an app every 5 minutes, without the need for scanning. The CGM device needs to be replaced periodically, usually every 14 days.   

Benefits of CGM in Diabetes Management 

One of the main benefits of using CGM in diabetes is less burden for the patient to adhere to a testing schedule. The data is either displayed in real-time or stored in the sensor and accessible by the receiver, so the patient does not have to check blood glucose levels via finger pricks. With this amount of data, patients can more precisely manage their blood glucose levels. Unlike a hemoglobin A1c level, or a single blood sugar level, CGM is particularly useful in tracking how glucose levels are changing over time, and in response to lifestyle factors such as exercise, meals, and sleep. Additionally, CGM displays blood glucose trends, which encourages proactive management, and reduces the risk of blood sugars becoming too low (hypoglycemia).

CGM in Functional Medicine Approach to Diabetes 

CGM in functional and integrative medicine provides more personalized and precise diabetes care. Patients can identify what factors trigger “spikes," or sharp elevations, in blood sugar, and therefore avoid them in the future. Additionally, the blood sugar response to changes in sleep, meal timing, and exercise can be tracked with CGM, allowing insight into the metabolic effects of lifestyle habits. Studies have shown that glucose spikes are associated with greater hunger, poorer mental health, poorer sleep, and greater mortality risk from cardiovascular disease. A functional and integrative medicine approach that emphasizes healthspan, will incorporate CGM to optimize these factors. A very important study characterized individuals into “glucotypes” based on their differing blood sugar response patterns to identical meals. This study highlighted the need for personalized dietary recommendations vs. standardized nutrition plans and the importance of monitoring the individual rise in blood sugar after meals. CGMs can help identify patterns in glucose levels over several days since the data is stored and available on the sensor and receiver. This can lead to more targeted lifestyle and dietary interventions and allows patients a broader perspective on their lifestyle choices.  

Patient Education and Empowerment Through CGM 

Because there are various CGM systems with different features, patient education for CGM should be collaborative and help them select the system that meets their clinical, socioeconomic, and lifestyle needs. Proper training is essential to empowering diabetes patients with CGM. Training on the CGM device should include proper sensor placement technique, how to check for sensitivity and allergic reactions to the device material, steps to set the target ranges and alerts, the significance of trend arrows, when to use a confirmatory fingerstick glucose check, how to receive and download CGM data, and how to share data with the clinical team. Additionally, patient education for CGM should also include information on prevention and treatment of hypoglycemia/hyperglycemia, and ensure patients are comfortable calculating and administering insulin doses.

Close and frequent follow-up is a great opportunity for empowering diabetes patients with CGM. Patients can develop self-awareness related to the impact of their habits on blood sugar regulation, and start to recognize symptoms of rising or dropping blood sugars. This will allow patients to be proactive in management, and modify behaviors to improve overall health. One study showed that 47% of CGM users reported that seeing a rise in their blood sugars increased their likelihood of going for a walk or doing physical activity, and 87% felt that they modified their dietary choices after using a CGM. In this same study, 90% of CGM users felt its use contributed to a healthier lifestyle.

Interpreting CGM Data for Optimal Care 

Clinicians can work with patients on interpreting CGM data for patterns and trends and identifying triggers for blood sugar spikes and drops. The first step is to ensure that patients are scanning their device at least once every 8 hours to ensure storage of data (if using a Freestyle Libre 2), and then connecting with the clinician via data share. CGM data in diabetes treatment can then inform nutritional, exercise, and medication recommendations. 

Close monitoring of not only the blood sugar measurement, but the variability between the high and low readings and the frequency of fluctuation, is also helpful in lowering the risk of developing chronic cardiovascular and metabolic disease. Large blood sugar variability can also contribute to inflammation, activation of stress hormones, and create harmful metabolic byproducts. 

Using a CGM can also help optimize lifestyle factors, such as sleep. This study using standardized meals, showed that poor sleep and later bedtimes led to elevated blood sugars after a standardized breakfast. Real-time feedback via CGM may create positive associations that impact beneficial behavioral changes.

Another important consideration in optimal diabetes care is the impact of low blood sugar or hypoglycemia. Hypoglycemia is a common side effect of some medications used to treat diabetes, such as insulin and sulfonylureas. Studies have shown hypoglycemia to negatively impact diabetes management and also cause symptoms of low energy, anxiety, and fear of recurrence. Using a CGM can significantly decrease the risk of hypoglycemia by proactively monitoring blood sugar trends and intervening early.

Challenges and Considerations in CGM Usage 

There are some considerations for CGM in diabetes. As the devices are comprised of multiple components, there is the possibility of malfunctioning. People who use CGMs should be trained in basic troubleshooting techniques, and connected with staff members for additional help if needed. Because the devices are placed directly on the body, some people may have skin irritation or reaction to the adhesive used on the sensor. The device itself is at risk of malfunctioning due to physical force, such as lying directly on the device. A big challenge in CGM usage is data overwhelm. Because there is a large amount of data constantly transmitted, users can become hyper-fixated on management, or overwhelmed by the next steps. Having a system in place to periodically meet with a clinician for data review can be helpful. Difficulty with dexterity, hearing, or vision can also present challenges in using the devices. Clinicians, especially in primary care, should become familiar and comfortable with the use of CGM and interpreting data as well. Lastly, at this time, the cost of a CGM remains high and may not always be covered by insurance. These can all present challenges in CGM usage and must be considered. 

Future Trends and Advances in CGM Technology 

Recent advances in CGM technology have occurred to create smaller and easier-to-apply devices, sensors with extended life and improved accuracy, and integration with other medical devices such as insulin pumps. There is increased public awareness about this revolutionary tool to manage glucose regulation in patients with and without diabetes.    

Continuous glucose monitoring has become the standard of care in type 1 diabetes and is widely used in people with type 2 diabetes as well. The future of CGM in diabetes care will include all people with diabetes, both on insulin and non-insulin therapies, to allow for more precise glucose control and fewer complications from the disease. In turn, this will lower hospital admissions and healthcare costs, and improve quality of life for those with this diagnosis. Additionally, CGM can be incorporated into the care of pregnant women with gestational diabetes, which will lower the risk of complications at delivery for both mother and baby.

Future applications of CGM will include people without diabetes, and it will be a tool to improve overall metabolic health by identifying glucose variability and subclinical disease. Since CGMs provide such rapid feedback about triggers for glucose spikes and drops, they can be utilized to create personalized lifestyle and dietary plans to minimize glucose variability. CGM could also be used as a behavior modification tool, but more research is needed on this application.

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Continuous Glucose Monitoring (CGM): Final Thoughts

The impact of CGM in revolutionizing diabetes care has been significant. It has encouraged a proactive, rather than a reactive, approach to managing blood sugars and places patient self-management at the center of the treatment plan. Optimizing the value of CGM in modern diabetes care will include data-driven personalized lifestyle and nutrition plans, in addition to more precise medication management. This will improve not only blood glucose control but also the overall metabolic health of a person. As functional medicine takes a holistic approach to health, CGMs should be widely incorporated to improve the overall health of a person.