Glucose values can be closely tied to sleep, and this relationship can actually work in both directions. A poor night of sleep can lead to elevated glucose values the following day, but higher glucose values can unfortunately also lead to poor sleep or feelings of fatigue.
The body considers sleep deprivation to be a chronic stressor that can lead to many hormonal imbalances. Both quantity and quality of sleep have an impact on blood glucose. Studies suggest that an inadequate amount of sleep can cause glucose to increase and decrease insulin sensitivity. On the other hand, disrupted sleep (sleep fragmentation can be particularly important for regulating hormone balance. Some studies have shown glucose values up to 25% higher after a restless night of sleep.
This means that a poor night of sleep can contribute to higher average values, higher fasting glucose, and higher postprandial spikes from food as a result of decreased insulin sensitivity.
While what we eat is still an essential contributor to our glucose values, clearly sleep plays an important role as well!
There are some specific nighttime glucose considerations that you may experience if you have pre-diabetes or type 2 diabetes, such as:
Are you seeing excessively high glucose values in the early morning hours? This could be the dawn phenomenon. All individuals, regardless of whether or not they have pre-diabetes or diabetes, experience a natural increase in blood sugar as certain hormones (growth hormone, cortisol, and catecholamines) cause the liver to release glucose into the bloodstream based on their normal circadian rhythm. This typically happens somewhere around 4 am to 8 am for most people.
In individuals without any blood glucose issues, insulin is released causing these higher values to come back down within a few hours.
Those of us with pre-diabetes or type 2 diabetes, however, may not secrete enough insulin and/or are resistant to that insulin, which means glucose continues to rise. This can lead to high fasting blood glucose values for a longer period than what we would ideally like to see.
It’s worth knowing that we may not be able to 100% resolve this issue, but in most cases, it can be minimized. Even if the Dawn Phenomenon isn’t resolved, you can still work on glucose values throughout the rest of the day to ultimately improve hemoglobin A1C as well as overall glucose values.
However, some things can help with the dawn phenomenon, such as:
Limit carbs before bedtime
Experiment with lower carb intake overall
Walk after dinner - other physical activities that you enjoy doing would also work!
Experiment with an earlier dinner mealtime
Some people find that eating a protein snack before bed can help stabilize glucose overnight and reduce spikes from dawn phenomenon. Experimenting while wearing a CGM can help you determine what works best for you.
Get good sleep (more on this below!)
Reduce stress (See Chapter 6)
If appropriate, talk with your doctor about whether or not adjusting your medication timing could help with this issue
Blood glucose going too low at night can be a sign of nocturnal hypoglycemia. If you’re seeing abnormal dips at night with your CGM, the first thing to note is that your CGM can read falsely low from pressure if you happen to sleep on the sensor at all. If this doesn’t seem to be the case, then you may be experiencing true nocturnal hypoglycemia.
If you do experience nocturnal hypoglycemia, it can be common to experience restless sleep, hot and clammy skin, shaking, changes in breathing, racing heartbeat, or even nightmares.
If you do observe nocturnal hypoglycemia in your CGM data or experience any of the signs listed above, refer back to the 15-15 rule for addressing hypoglycemia in Chapter 2 - Section 2 to resolve this issue quickly.
Once you’ve safely gotten yourself out of that hypoglycemic episode, it’s important to try to understand what led to that episode. While this is generally most common in people who are taking insulin, it can happen in those who are not for several different reasons including (but not limited to):
Metabolic inflexibility combined with fasting and/or skipping meals (particularly dinner)
Alcohol intake - drinking alcohol in the evenings can cause glucose to dip overnight
Late evening exercise without adequate re-fueling
Certain additional medical conditions, such as hypothyroidism or adrenal insufficiency
Once you have a handle on the why behind that nocturnal hypoglycemic episode, it can become a lot easier to understand what adjustments to begin experimenting with to try to avoid that from happening in the future. Your NutriSense nutritionist can help to support you on this journey, and it’s important to let your primary care team know about this as well.
Next: Sleep Hygiene