An expert opinion on Continuous Glucose Monitoring

A Continuous Glucose Monitor (CGM) lives up to its name by providing continuous monitoring of glucose levels (sugar) in the blood.

The surge in popularity of CGMs has transcended beyond the diabetic community, sparking a new trend across the general public. With initiatives like the ZOE study and offerings from apps like Lingo Veri, and UltraHuman, individuals now have access to insights into their body's inner workings and are proudly displaying their CGMs on their arms.

Yet, amidst this frenzy, questions arise: Is the hype surrounding CGMs justified? Should they be accessible to everyone, even those without diabetes? Or perhaps we have ventured too far into the realm of health technology in everyday life?

Natalie Burrows, a CardioMetabolic health specialist with a mission to prevent and reverse type 2 diabetes, and Clinical Director at Integral Wellness, delves into the nuances of CGMs, exploring their benefits and drawbacks.

A Continuous Glucose Monitor (CGM) measures blood glucose levels in the interstitial fluid, typically worn on the arm, buttocks, or torso. This method differs slightly from the capillary blood measured by traditional finger prick monitors, long utilised in diabetes management.

The advent of CGMs marks a significant shift in diabetes care, offering relief from frequent finger pricks. This enhanced convenience fosters better compliance with blood sugar monitoring and subsequently improves management for individuals with diabetes, regardless of type.

Diabetes encompasses various types:

• Type 1 diabetes, constituting approximately 8% of cases, is an autoimmune condition where pancreatic cells fail to produce insulin.

• Type 2 diabetes primarily stems from dietary and lifestyle factors, with certain risk factors predisposing individuals to its onset. It accounts for 90% of diagnosed diabetes cases.

• Gestational diabetes manifests as elevated blood sugar levels during pregnancy.

• Type 1.5 diabetes, or LADA (Latent Autoimmune Diabetes in Adults), presents similarly to type 2 diabetes but is an autoimmune condition that develops in adulthood, potentially leading to misdiagnosis.

• Type 3c diabetes arises as a secondary condition due to other ailments disrupting pancreatic insulin production, such as pancreatitis.

Following NICE guidelines, the NHS can prescribe CGMs to insulin-dependent individuals, irrespective of diabetes type. However, CGMs are increasingly gaining popularity among a broader user base, extending beyond those with a diagnosis.

Studies indicate the profound impact of real-time data on driving behavioural changes. Continuous Glucose Monitors (CGMs) play a pivotal role in raising awareness of lifestyle impacts and facilitating healthier choices by offering instant feedback. As individuals witness benefits like increased energy, reduced cravings, and weight loss, they are motivated to sustain changed behaviours and adopt new habits.

Everyone with diabetes will find a CGM beneficial in the management and potential improvement of their condition. However, aside from this group of individuals, there is an argument for the use of CGMs within the general population either due to a different condition or based on a myriad of symptoms. 

Pre-diabetic Individuals

Individuals at risk of developing diabetes can utilise CGMs to monitor their glucose levels in real-time, providing valuable insights into the dietary and lifestyle factors influencing blood glucose spikes and fluctuations. This early awareness facilitates proactive adjustments, including dietary modifications and increased physical activity, to halt the progression to full-blown diabetes.

Athletes

CGMs can be valuable for athletes to optimise their nutrition and performance by tracking glucose levels before, during, and after exercise. Understanding blood glucose levels, which are influenced differently depending on the type and duration of exercise, athletes can tailor their carbohydrate intake to match their energy needs more accurately, ensuring optimal fueling without risking energy crashes or ‘bonking’ (where muscles run out of fuel).

Weight Management 

Elevated blood glucose levels and insulin resistance can hinder fat loss and disrupt appetite regulation making weight management for some people challenging as a result. CGM data can inform the food and lifestyle approach to stabilise blood sugar levels and minimise insulin spikes which can lead to weight loss or stablisation - whatever the goal is. 

Metabolic Disorders

Individuals with metabolic disorders other than diabetes, such as insulin resistance or metabolic syndrome (which puts someone at higher risk of type 2 diabetes and includes higher body weight, blood pressure, high triglycerides, low HDL and impaired fasting blood glucose) can use CGMs to monitor their glucose levels and take control of their conditions more effectively. High blood pressure and an unhealthy cholesterol profile are intrinsically linked to higher or fluctuating blood glucose levels.

Symptoms of Fatigue

Fluctuations in blood glucose levels can have an impact on fatigue since glucose serves as the main energy source. When glucose levels drop or cells fail to respond to insulin, impairing glucose uptake, mitochondrial function suffers. This compromises energy/ATP production, leading to fatigue. Furthermore, disrupted mitochondrial function can induce oxidative stress, exacerbating fatigue. Thus, maintaining stable blood glucose levels, aided by insights from a CGM, can help mitigate fatigue.

Research and Healthcare Professionals

CGMs are valuable tools for researchers studying glucose metabolism, as well as healthcare professionals monitoring patients' glucose levels in clinical settings (which is why I wear one on occasion).

Other Symptoms

CGMs can be helpful for anyone who wants to get rid of the symptoms we’ve begun to normalise but can be caused by fluctuating blood glucose levels, including:

• Low energy

• Waking up unrested

• Cravings

• Inability to fast between meals (always needing a snack)

• Waking up in the middle of the night

• Slow wound healing or recovery from illness

But this doesn’t give a hall pass to everyone nor does it mean everyone should use a CGM.

Using a CGM to understand how you respond to food, drinks and certain lifestyle choices can drive positive change. I’ve mentioned how studies show people are more motivated to make changes when they have access to real-time data - similar to a step tracker. 

CGMs are also a great way to visually see why you may get that energy slump in the afternoon or wake up at 3 am every night. 

However, as with all health tech, it’s not suitable for everyone. Here are some considerations for when the CGM data may backfire from beneficial to unhealthful.

• Someone who has an eating disorder, disordered eating or tendency to restrict food (past or present)

• An individual with a history or potential to experience Health or Food Anxiety

• When an addictive personality is identified

• If the individual's neurodiversity puts them at risk of an obsession

In these individuals, it is not advised to use data tracking such as a CGM or other forms of daily food and lifestyle trackers. A positive relationship with food is always at the heart of using a CGM and any risk to the contrary should be avoided. 

While men and women both experience hormonal fluctuations, women face unique challenges in managing hormonal health due to the complexities of the menstrual cycle. 

This cycle, typical for reproductive-age women, consists of four phases: menstruation, follicular, ovulation, and luteal. During the follicular phase, estrogen levels rise, followed by ovulation mid-cycle and a subsequent rise in progesterone during the luteal phase, accompanied by a decline in estrogen. It's often during the luteal phase that women report a reduction in energy and an increase in food cravings. 

Research suggests that blood glucose levels fluctuate throughout the menstrual cycle, with evidence indicating that many women may experience elevated blood glucose levels concurrently with higher estrogen levels, particularly during ovulation when luteinizing hormone levels also rise significantly. These elevated blood glucose readings correspond with reported increases in cravings and decreased energy levels. 

While the menstrual cycle can indeed affect glucose and insulin sensitivity, studies on glucose levels and insulin sensitivity throughout the menstrual cycle yield mixed findings. For instance, in one  study  involving 231 participants, the impact on blood glucose ranges across menstrual cycles was less than 2%. 

Each woman's experience of blood sugars across their cycle is unique, with some experiencing changes that drive repeated symptoms. Wearing a CGM for a few cycles could help women better manage hormonal symptoms by understanding and adapting their diet, lifestyle, exercise, and sleep patterns accordingly. 

Additionally, women, who are more prone to lower iron levels and anaemia, may be at risk of being missed for signs of high blood sugars due to the impact of low iron levels on HbA1c readings, the gold standard test for diagnosing diabetes. In such cases, a CGM could serve as a valuable diagnostic tool alongside fasting glucose levels and oral glucose tolerance tests.