What a continuous glucose monitor can teach you about your health

Continuous glucose monitors (CGMs) are becoming increasingly popular, not only among people with diabetes but also among individuals curious about their metabolic health.

Once mainly used in diabetes management, these wearable devices are now being explored by people interested in understanding how food, sleep, stress, exercise, and everyday habits affect blood glucose levels.

But what exactly can a CGM tell us, and do you really need one?

What is a continuous glucose monitor?

A continuous glucose monitor is a small wearable device, usually placed on the back of the upper arm, that measures glucose levels in real time throughout the day and night. Unlike a standard blood test, which provides a snapshot of glucose at one moment in time, a CGM allows users to see patterns and fluctuations over days or weeks.

For some people, this information can provide valuable insight into how their body responds to meals, stress, sleep, physical activity, or even hormonal changes.

Although CGMs were originally developed for people with diabetes, some newer versions, such as the Lingo monitor, are designed for the general public interested in tracking metabolic health.

Why blood sugar matters

Glucose is the body’s primary source of energy. After eating, carbohydrates are broken down into glucose, which enters the bloodstream and is regulated by insulin. Ideally, blood sugar levels rise and fall in a relatively balanced way.

However, frequent spikes and crashes in blood glucose may contribute over time to low energy, cravings, mood changes, increased hunger, and potentially insulin resistance in susceptible individuals.

What many people do not realise is that blood sugar is influenced by far more than food alone. While meals certainly play a role, factors such as stress, sleep quality, exercise, illness, and hormones can all significantly affect glucose regulation.

Blood sugar is about more than food

When people think about blood sugar, they often immediately think about sugary foods or carbohydrates. Yet real-life glucose patterns are often more complex.

Stress and blood sugar

Stress can have a surprisingly powerful effect on glucose levels.

When the body perceives stress, whether physical or emotional, it releases hormones such as cortisol and adrenaline as part of the well-known “fight or flight” response. This process helps mobilise energy by releasing stored glucose into the bloodstream, preparing the body to respond to perceived danger.

This may have been useful when humans were escaping sabre-toothed tigers, but modern-day stressors such as work pressures, family responsibilities, financial worries, poor time management, and lack of downtime can trigger the same physiological response.

For some people, ongoing stress may contribute to cravings, disrupted sleep, irritability, and feeling generally “wired but tired”.

Sleep and glucose regulation

Sleep quality also appears to play a significant role in blood sugar balance.

Poor sleep or insufficient sleep may influence insulin sensitivity, appetite regulation, hunger hormones, and food choices the following day. Many people notice that after a poor night’s sleep, they feel hungrier, crave sugary foods, and have lower energy.

Research increasingly suggests that poor sleep can influence metabolic health in ways we are only beginning to fully appreciate.

Meal composition matters

One of the most interesting things a CGM may reveal is that not all meals affect blood glucose in the same way.

The balance of protein, fibre, fats, and carbohydrates within a meal may significantly influence how quickly glucose rises. For example, pairing carbohydrates with protein and fibre often helps slow digestion and may result in a steadier glucose response.

Simple food swaps can sometimes make a noticeable difference. This may include choosing higher-protein or higher-fibre carbohydrate options, adding protein to breakfast, or building meals with more balance overall.

What a CGM may reveal

One of the biggest advantages of using a CGM is the opportunity to observe your own personal patterns.

Two people can eat exactly the same meal and experience different glucose responses. Factors such as sleep, stress, movement, muscle mass, hormones, genetics, and overall metabolic health can all influence the result.

Rather than focusing on perfection, a CGM can encourage curiosity.

Questions people often begin asking include:

• Does skipping breakfast affect my energy or cravings? 
• How does poor sleep affect me the next day? 
• Does stress impact my eating habits? 
• Which meals help me feel more energised and balanced?
• Are there certain foods that leave me feeling hungry again shortly afterwards? 

For some people, seeing data in real time can make healthy habits feel more tangible and motivating.

My 14-day CGM experience

Out of professional curiosity, and because I have a family history of Type 2 diabetes, I decided to wear a Lingo CGM for two weeks. What surprised me most was not the food.

My glucose responses after meals were generally stable, with post-meal readings usually staying within a healthy range. However, what stood out far more clearly was the impact of stress and poor sleep.

On busier, more stressful days, my glucose readings often rose despite eating well. Similarly, after poor sleep, glucose levels appeared less stable the following day. This was a valuable reminder that lifestyle habits extend far beyond what is on our plate.

Interestingly, I also noticed that small food swaps appeared to influence my glucose response. For example, meals made with pea or lentil pasta instead of standard wheat pasta seemed to lead to steadier glucose patterns for me.

The experience also encouraged me to revisit habits I already knew were important but had perhaps not prioritised enough.

I made more effort to prepare for busy mornings the night before, introduced gentle stretching before starting the day, focused more intentionally on protein-rich breakfasts, reduced evening snacking, and became more consistent with sleep habits.

Perhaps the most unexpected outcome was that wearing a CGM increased my awareness of how certain foods made me feel. Seeing real-time feedback encouraged me to reduce added sugar and ultra-processed snacks, something I had wanted to improve for quite some time.

Do you need a CGM?

Not necessarily.

A CGM is not essential for good health, and many people can improve blood sugar balance through well-established lifestyle habits such as balanced meals, regular movement, stress management, and prioritising sleep.

However, for some individuals, particularly those curious about their metabolic health or wanting greater awareness of how their lifestyle affects energy and cravings, a CGM may offer useful insight.

It is important to remember that glucose readings should be viewed as information, not judgment. The goal is not perfection or obsessively chasing “perfect” numbers, but understanding patterns and learning more about your own body.

People with Type 2 diabetes should seek advice from their healthcare provider about the most suitable monitor for their needs. Likewise, individuals with a history of disordered eating may wish to speak with a healthcare professional before using a CGM, as constant tracking may not be appropriate for everyone.

Ultimately, whether or not you use a CGM, one of the most valuable lessons remains the same: blood sugar balance is influenced not only by what we eat, but also by how we sleep, move, manage stress, and care for ourselves day to day.

References

1. Jarvis PRE, et al. Continuous glucose monitoring in a healthy population: understanding the post-prandial glycemic response in individuals without diabetes mellitus. Metabolism. 2023 Sep;146:155640.  https://pubmed.ncbi.nlm.nih.gov/37356796/

2. Chekima K, at al. Utilising a Real-Time Continuous Glucose Monitor as Part of a Low Glycaemic Index and Load Diet and Determining Its Effect on Improving Dietary Intake, Body Composition and Metabolic Parameters of Overweight and Obese Young Adults: A Randomised Controlled Trial. Foods. 2022 Jun 15;11(12):1754. https://pubmed.ncbi.nlm.nih.gov/35741952/