The CGM Blog
How Can I Control My Blood Sugar at Night?
The content in this article should not be taken as medical advice. Please consult your healthcare provider regarding your individual health needs.**
Managing your blood sugar at night can feel frustrating because you’re not awake to keep an eye on it. Not knowing where your blood sugar levels are headed while you’re asleep can also cause feelings of anxiety or fear. Many individuals in the diabetes community express having these emotions around managing blood sugar at night, so know that you’re not alone in experiencing them. Most cases of hypoglycemia, or low blood sugar, happen at night. Hyperglycemia, or high blood sugar, can also happen while you’re asleep, especially in the early morning hours. Learning to identify the signs of high and low blood sugar at night can help you determine what factors are influencing your glucose control and help you manage your blood sugar with greater peace of mind.
For shift workers who have to work mixed hours or overnight, managing blood sugar means taking into account a varied schedule and changing meal and sleep times. Going against the body’s natural sleep cycle has a major impact on glucose levels.
It’s more than possible to find ways to regulate your blood sugar at night to help you feel your best during the day. Together with your doctor, you can come up with a plan to keep your blood sugar stable through the night—whether you’re asleep during that time or not.
Understanding Low Blood Sugar at Night
Nighttime hypos, also called nocturnal hypoglycemia, happen when you experience low blood sugar while you sleep. Because you’re not eating anything for several hours when you’re asleep, serious lows are more likely to happen at night than during the day.5
It can be hard to know if you’ve had a nighttime hypo because you’re asleep when they happen. A non-exhaustive list of a few of the most common signs of a nighttime hypo include:6
- Night sweats, waking up with damp clothes or sheets.
- Waking up with a headache.
- Having nightmares.
- Feeling very tired when you get up in the morning.
- Experiencing a rebound spike in glucose levels—noticing a glucose reading that is higher than normal when you measure in the morning.
You may also experience anxiety or rapid heartbeat before falling asleep, which could indicate the potential for experiencing a nighttime hypo.6
Understanding High Blood Sugar at Night
Even though you’re not consuming food, blood sugar can go high while you sleep. Many people also experience high blood sugar in the early morning when they wake up.3 Like nighttime hypos, having high sugars at night has no single cause. It can happen when you eat a sugary snack or high-carb meal. It can also happen because there isn’t enough insulin in your body overnight.7
Just a handful of the signs of having high blood sugar overnight include:7
- Having a rough, restless sleep.
- Waking up with a dry mouth or feeling thirsty.
- Urinating frequently during the night.
- Experiencing nausea or a headache.
You might also experience symptoms like increased thirst and urination during the day following if you’ve had hyperglycemia during the night.7
High blood sugars in the early morning can be caused by something called the dawn phenomenon. This process occurs in everyone—not just those living with diabetes—when hormones in the body signal to the liver to produce more glucose to give your body the energy it needs to wake up. The challenge is that your insulin levels might be too low at this time to compensate for the increase in glucose. If you’re having highs in the morning, talk to your doctor about your options for treating it.3
How to Stabilize Your Blood Sugar Overnight?
Many factors affect changes in blood sugar. Be aware that while there are things you can do to help prevent a nighttime hypo, you may not be able to control all the variables that might be affecting you. It’s important to speak with your doctor if you’re regularly experiencing nighttime hypos to determine which treatment and prevention options are best for you.
Nighttime hypos and high blood sugar at night can happen for a variety of reasons. If you are experiencing a lot of variability in your glucose levels overnight, there are a few things you might want to take a look at in your bedtime routine.
Be mindful about when you exercise. Having a very active day or exercising close to when you want to sleep can lower your glucose levels. Spending a long time doing cardio, such as running, biking, or swimming, can increase insulin sensitivity for up to 48 hours.6,8 If you rely on insulin, it’s important to be aware of how exercise impacts your glucose levels and take it into account when you’re getting ready for bed.
Pay attention to your insulin dosage. Too much basal insulin (the steady stream of insulin usually in the form of either a long acting injection or the insulin that a pump provides on an ongoing basis) can lead to a nighttime hypo because there is no glucose coming into your body to balance it out.6 Each type of insulin impacts the body differently, so be aware of which you’re using at night, and how much.1,5 Overcorrecting your insulin dose to prevent a hypo can cause high blood sugar.7
Consider the impact of drinking alcohol before bed. For individuals who rely on insulin, having a drink with dinner or drinking two to three hours after your evening meal can result in low blood sugar overnight or the next morning. Drinking alcohol can lower blood sugar levels up to 24 hours afterwards.9 If you’re drinking alcohol, regularly check your glucose levels throughout the evening and make sure to eat a meal or snack, especially if you’re dancing or doing physical activity.9
Stick to a regular meal schedule. Skipping dinner, eating a high-glucose meal such as pizza, or having a snack close to bedtime can influence your glucose levels while you’re sleeping. Eating at the same times every day can make it easier to see how your meals impact your glucose levels, helping you prevent high and low blood sugar at night.6 Keep glucose tablets or a sugary snack or drink next to your bed so that you can treat a nighttime hypo if you’re experiencing one.5,10
Check your glucose levels before bed, and again between midnight and 3 am every night. Knowing where your glucose is at before you fall asleep gives you the chance to take precautions to prevent high and low blood sugar. Measuring again between midnight and 3 am further gives you a better idea of how your glucose levels change overnight as you sleep. Even though waking up to check your glucose can be disruptive to your sleep (and getting a good night’s sleep is important!), having this information can help you and your diabetes healthcare team make adjustments to your insulin doses, medication, or meal plan.7
Blood Sugar Management and Shift Work at Night
Shift work often requires individuals to go against their body’s natural cues to go to sleep, and many experience insomnia. This has an impact on appetite and the way glucose is used in the body.11 Managing diabetes while doing shift work is about being prepared. You and your doctor can devise a glucose management strategy that works for you and your schedule. Here are some general tips for taking care of your glucose levels while doing shift work:12
- Plan and prep your meals and snacks for the week ahead. This will help you avoid last-minute trips to vending machines or fast-food restaurants.
- You may be too tired to make yourself a healthy meal after a long shift. Keep healthy, ready-to-eat snacks and meals in your fridge for when you get home.
- Sometimes it can be hard to get away for a snack break. Always have planned and emergency snacks on you while you work.
Continuous Glucose Monitoring Supports Glucose Management at Night
Managing glucose at night takes some serious detective work and can take a toll on your much-needed rest. A continuous glucose monitoring system (CGM) like a Dexcom CGM System is a great tool for helping you figure out what might be causing nighttime highs or lows. Dexcom CGM collects glucose data while you sleep, so you don’t have to disrupt your sleep to wake up in the wee hours to check your glucose. But, if you are experiencing a high or a low during the night, the system can alert you so that you can take action.
Unlike a blood glucose meter, which measures sugar levels in your blood, a CGM provides glucose readings through real-time measurement of interstitial fluids just beneath your skin. Some CGM systems like the Dexcom G6 or Dexcom G7 can display your glucose number value as well as trend arrows that show the speed and direction your glucose is heading. These insights from your CGM can give you even more information to make appropriate diabetes treatment decisions while managing your or helping your loved one manage their diabetes.
For instance, the predictive, Urgent Low Soon alert lets you know up to 20 minutes before a serious low below 3.1 mmol/L.‡ There is also the Urgent Low alarm that can’t be turned off, which notifies you when your glucose levels have dropped below 3.1 mmol/L. You can also customize alerts to let you know when your glucose levels have gone too high. These alert features give you a little extra peace of mind when you sleep, knowing you’ll be woken up when necessary.
A Dexcom CGM System makes it easy to review your glucose patterns over a period of time to see what’s going on at night. And with access to your glucose data in the palm of your hand on a compatible smart device* or receiver, you can easily check your glucose levels wherever you are.†
Monitoring your glucose levels is particularly important if you’re a shift worker with a varied schedule. Be sure to check your glucose levels before you go to sleep, especially if your sleep time is different day-to-day. Keeping an eye on your glucose levels throughout your shift using a CGM system can also help you understand how different eating and sleeping patterns affect you so you can make the healthiest choices possible in the moment.
Learn how Dexcom CGM Systems can help you get more insight into what affects your glucose levels, empowering you to determine healthy ways to keep your glucose levels stable throughout the day and night.
*For a list of compatible smart devices, please visit dexcom.com/compatibility
** The content in this article should not be taken as medical advice. Please consult your healthcare provider regarding your individual health needs.
†If your glucose alerts and readings from the Dexcom G6 do not match symptoms or expectations, use a blood glucose meter to make diabetes treatment decisions.
‡ Provides a warning up to 20 minutes in advance of severe hypoglycemia (glucose levels at or below 3.1 mmol/L).
** The content in this article should not be taken as medical advice. Please consult your healthcare provider regarding your individual health needs.
†If your glucose alerts and readings from the Dexcom G6 do not match symptoms or expectations, use a blood glucose meter to make diabetes treatment decisions.
‡ Provides a warning up to 20 minutes in advance of severe hypoglycemia (glucose levels at or below 3.1 mmol/L).
1 Hendrieckx C, et. al. Diabetes and emotional health: a practical guide for health professionals supporting adults with type 1 or type 2 diabetes. American Diabetes Association. 2021. https://professional.diabetes.org/meetings/MentalHealthWorkbook
2 Hypoglycemia Nocturnal. Johns Hopkins Medicine. Accessed May 29, 2023. https://www.hopkinsmedicine.org/health/conditions-and-diseases/diabetes/hypoglycemia-nocturnal.
3 High Morning Blood Glucose. American Diabetes Association. Accessed May 29, 2023. https://diabetes.org/diabetes/treatment-care/high-morning-blood-glucose.
4 Shift Work Can Harm Sleep and Health: What Helps? Harvard Health Publishing. February 20, 2023. https://www.health.harvard.edu/blog/shift-work-can-harm-sleep-and-health-what-helps-202302282896
5 Yale JF, et al. Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada: Hypoglycemia. Can J Diabetes. 2018;42 Suppl 1:S104-S108. doi:10.1016/j.jcjd.2017.10.010
6 Avoiding Nighttime Hypoglycemia. Joslin Diabetes. Accessed May 25, 2023. https://www.joslin.org/patient-care/diabetes-education/diabetes-learning-center/avoiding-nighttime-hypoglycemia
7 What to Do When Blood Sugar is High at Night. DiaTribe. Accessed May 29, 2023. https://diatribe.org/high-blood-sugar-night-what-do
8 Sigal R, et al. Physical Activity and Diabetes. Canadian Journal Of Diabetes. 2018;42(Supp 1):S54-S63. doi: 10.1016/j.jcjd.2017.10.008
9 Alcohol and Diabetes. Diabetes Canada. Accessed May 29, 2023. https://www.diabetes.ca/DiabetesCanadaWebsite/media/Managing-My-Diabetes/Tools%20and%20Resources/alcohol-and-diabetes.pdf?ext=.pdf
10 Nocturnal Hypoglycemia. Diabetes.co.uk. Updated January 25, 2023. https://www.diabetes.co.uk/nocturnal-hypoglycemia.html
11 Wu Q-J, et al. Shift work and health outcomes: an umbrella review of systematic reviews and meta-analyses of epidemiological studies. Journal of Clinical Sleep Medicine. 2022;18(2):653–662. doi:10.5664/jcsm.9642
12 HealthLink BC. Quick Tips: Diabetes and Shift Work. Published 2023. Updated July 28, 2021. https://www.healthlinkbc.ca/illnesses-conditions/diabetes/quick-tips-diabetes-and-shift-work
2 Hypoglycemia Nocturnal. Johns Hopkins Medicine. Accessed May 29, 2023. https://www.hopkinsmedicine.org/health/conditions-and-diseases/diabetes/hypoglycemia-nocturnal.
3 High Morning Blood Glucose. American Diabetes Association. Accessed May 29, 2023. https://diabetes.org/diabetes/treatment-care/high-morning-blood-glucose.
4 Shift Work Can Harm Sleep and Health: What Helps? Harvard Health Publishing. February 20, 2023. https://www.health.harvard.edu/blog/shift-work-can-harm-sleep-and-health-what-helps-202302282896
5 Yale JF, et al. Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada: Hypoglycemia. Can J Diabetes. 2018;42 Suppl 1:S104-S108. doi:10.1016/j.jcjd.2017.10.010
6 Avoiding Nighttime Hypoglycemia. Joslin Diabetes. Accessed May 25, 2023. https://www.joslin.org/patient-care/diabetes-education/diabetes-learning-center/avoiding-nighttime-hypoglycemia
7 What to Do When Blood Sugar is High at Night. DiaTribe. Accessed May 29, 2023. https://diatribe.org/high-blood-sugar-night-what-do
8 Sigal R, et al. Physical Activity and Diabetes. Canadian Journal Of Diabetes. 2018;42(Supp 1):S54-S63. doi: 10.1016/j.jcjd.2017.10.008
9 Alcohol and Diabetes. Diabetes Canada. Accessed May 29, 2023. https://www.diabetes.ca/DiabetesCanadaWebsite/media/Managing-My-Diabetes/Tools%20and%20Resources/alcohol-and-diabetes.pdf?ext=.pdf
10 Nocturnal Hypoglycemia. Diabetes.co.uk. Updated January 25, 2023. https://www.diabetes.co.uk/nocturnal-hypoglycemia.html
11 Wu Q-J, et al. Shift work and health outcomes: an umbrella review of systematic reviews and meta-analyses of epidemiological studies. Journal of Clinical Sleep Medicine. 2022;18(2):653–662. doi:10.5664/jcsm.9642
12 HealthLink BC. Quick Tips: Diabetes and Shift Work. Published 2023. Updated July 28, 2021. https://www.healthlinkbc.ca/illnesses-conditions/diabetes/quick-tips-diabetes-and-shift-work