Stress, Hormones & Your CGM Data

How non-food factors can make a difference for your glucose

What you eat can have a significant impact on your blood glucose, but it’s far from the only factor. Your hormone levels also play a significant role in determining how your body processes glucose. Being aware of these factors can help you to interpret the data from your Continuous Glucose Monitor (CGM).

The Full Hormonal Cast

A variety of different hormones can impact glucose levels, including stress hormones, thyroid hormones, sex hormones, and growth hormones.

Stress hormones generally increase blood sugar levels. When you encounter any type of stress, the body produces hormones like cortisol, adrenaline, and noradrenaline. These hormones decrease insulin sensitivity throughout the body. They also trigger the liver to produce extra glucose, which can increase blood sugar even if you haven’t eaten anything recently. 

The body’s glucose response is also affected by thyroid hormones, which are hormones that impact the body’s use of energy. High thyroid hormone levels (hyperthyroidism) generally increase blood sugar by triggering glucose release from the liver. Hyperthyroidism also causes insulin to be removed from the blood more quickly, which can increase glucose levels by giving insulin less time to clear blood sugar after a meal.

By contrast, low thyroid hormone levels (hypothyroidism) generally slow down metabolism. This decreases blood sugar in the short term, by keeping insulin active in the bloodstream for longer. However, hypothyroidism also promotes weight gain, which can lead to insulin resistance and higher glucose levels over the longer term.

Another hormone that can impact glucose levels is growth hormone (GH). GH generally increases blood sugar by reducing insulin sensitivity and triggering the release of glucose from the liver. A bout of intense exercise can increase GH levels for 1-2 hours afterward, as this hormone provides the stimulus for building muscle tissue. During this period, blood sugar may temporarily be elevated.

Sex hormones also impact glucose levels. Both estrogen and testosterone tend to promote insulin sensitivity in the body. This helps to explain why both women and men often experience increases in blood sugar levels as they age – as levels of these sex hormones drop, there’s a corresponding decrease in insulin sensitivity.

However, progesterone has the opposite effect, and tends to promote insulin resistance. Levels of progesterone rise and fall as part of the menstrual cycle, which leads to changes in glucose control during different phases of the cycle.

The Menstrual Cycle and Glucose

For women who have not yet gone through menopause, glucose control is impacted by the monthly cycle.

In the first half of the menstrual cycle, estrogen levels are high. Because estrogen tends to promote insulin sensitivity, most women notice that their blood glucose control is relatively good in this period.

After ovulation, progesterone levels begin to rise. Progesterone levels are at their highest about a week before your period begins. Because progesterone tends to cause insulin resistance, it’s not surprising that many women notice that their glucose is slightly more elevated during this part of their cycle.

Many women also experience cravings as part of the menstrual cycle. Cravings for sweet foods are most common in the later part of the cycle. Progesterone is also high during this time, meaning that you’re craving sweets at the time when your body is the least prepared to handle the extra sugar 

If you tend to experience cravings, keep some healthy snacks around during this part of your cycle. High-protein, low-carb snack options can help to satisfy your cravings without causing a blood sugar spike. For example, plain yoghurt, fresh fruits, light popcorn, or baked nuts could all be good options. Experiment with different snacks until you find one that feels satisfying but also doesn’t cause a spike in your glucose levels.

During perimenopause (the transition period before menopause), fluctuations in estrogen levels often lead to corresponding fluctuations in blood sugar levels. Once a woman has gone through menopause, her estrogen levels drop very low, which tends to reduce her insulin sensitivity and lead to increased blood glucose levels.

Illness and Glucose

An injury, illness, or infection creates a physical stress on the body. The body responds by producing stress hormones like cortisol, which tend to raise glucose levels.

That’s why, when you’re experiencing an illness or have had a major injury or surgery, you might notice that your glucose level is more volatile during your recovery period. Even a relatively minor infection, such as a common cold, can trigger the release of stress hormones as part of the body’s normal physiological response, and this can significantly raise fasting glucose levels. 

Your glucose control will likely improve as your body recovers. If you notice increases in your blood sugar levels while you’re recovering from an illness, it’s important not to take this as a sign of long-term deterioration in your metabolic health. Instead, it’s a temporary state caused by your body’s healing response.

Meditation and Breathing Exercises

Meditation can be used to activate parts of the nervous system that are associated with the relaxation response, such as the vagus nerve. This has been shown to lower cortisol levels, which in turn can reduce blood sugar levels.

Breathing exercises offer a quick way to activate the nervous system’s relaxation response. 

One common exercise is 4-7-8 breathing. Breathe in through your nose for 4 seconds, hold your breath for 7 seconds, and then breathe out through your mouth for 8 seconds. (If holding your breath for 7 seconds isn’t comfortable for you, you can shorten the breath hold. However, try to maintain the 4-second inhale and 8-second exhale.) 

Keep doing this for at least 10 minutes if you can, but even a shorter session of deep, slow breathing can help to shift the nervous system into a more relaxed state. Consider doing breathwork at least once per day, or after heavy mealsThis is also a useful tool to use whenever you’re feeling stressed.

What You Can Do Today

Keeping in mind the non-food factors that can influence glucose control can help you to interpret your CGM data better. 

It’s a great idea to annotate your glucose data with notes about the context. Make notes about events like workouts or giving a presentation at work, along with the time they occurred. If you don’t sleep well one night, note that the next morning. If you’re a woman in your premenopausal years, note when your period occurs so that you can compare your glucose levels in different phases of your cycle.

This builds a richer picture of your metabolic story, and helps you to understand how factors beyond food could be influencing your glucose control.