Managing Low Blood Sugar Overnight

Managing type 1 diabetes (T1D) is a round-the-clock job—even when you need to sleep. Making sure that your glucose levels stay within your target range at nighttime can be challenging. Diabetes Canada defines the general target range as 3.9–10.0 mmol/L. If your glucose falls below your target range during the night, you might be at risk of nocturnal hypoglycemia, also called nighttime hypoglycemia, nighttime hypos, or nighttime lows.
Nighttime hypoglycemia may wake you up at night, but many people sleep through it and see symptoms in the morning. Among many of the clues that could indicate that you’ve had a nighttime hypo, a few include,
  • being restless, talking in your sleep, or having nightmares
  • racing heart, fast breathing, or shaking
  • feeling very tired in the morning
  • having a bad headache
  • having night sweats
Experiencing nocturnal hypoglycemia can be frustrating and exhausting. Having nighttime hypos and checking for them can also disrupt your sleep. You may need to wake up during the night to make sure your blood sugar isn’t too high or low, or your symptoms might prevent you from getting a full night of rest. If you’re the parent of a child who is living with T1D, you might have to wake up your child in the middle of the night and check their glucose levels to ensure that they aren’t experiencing hypoglycemia.
If you think that you or your loved one may be dealing with nighttime hypoglycemia or if you’re looking to understand how to prevent it, the first step is to talk to your doctor. Hypoglycemia is very serious; it’s safer to prevent it from happening than to treat it after it happens.
Why Does My Blood Sugar Drop at Night?
People living with type 1 diabetes are at a higher risk for experiencing hypoglycemia in general compared to those living with type 2 diabetes (T2D).4 That said, those living with T2D managed by insulin are similarly at risk of hypoglycemia. This means these folks are more likely to experience nocturnal hypoglycemia.4 To understand why your blood sugar drops at night, it’s a good idea to learn more about why hypoglycemia happens in the first place.
For people living with T1D, managing the body’s glucose levels is extremely hands-on as the pancreas no longer produces insulin. Insulin is the hormone responsible for making sure that the glucose in the blood can be absorbed by the cells in the body to be used for energy. Individuals living with T1D must treat it with insulin injections to replace the insulin that the pancreas would normally provide. When there’s excess insulin in the bloodstream, it causes too much glucose to be absorbed, which can result in hypoglycemia if the amount of blood sugar is not replenished. Just one of the many potential triggers for hypoglycemia is exercise. During and after exercise, insulin sensitivity increases throughout the body and muscle absorbs glucose faster because it doesn’t need insulin to do so when it’s active. The extra insulin in the bloodstream further reduces blood sugar levels.
Hypoglycemia can happen at any time but it’s more difficult to catch it and treat it when you’re asleep. During the day, you may recognize the symptoms of hypoglycemia and eat something sugary to quickly bring your glucose back into your target range. A few of the symptoms of hypoglycemia include9:
  • Sweating
  • Trembling
  • Fast heartbeat
  • Hunger
  • Dizziness
  • Difficulty speaking
  • Confusion
At night, not eating enough after your evening dose of insulin or taking a larger dose than normal can have an impact on your glucose levels while you sleep, resulting in a nighttime hypo.2 A few other reasons nighttime hypos might occur include skipping dinner, exercising before bed, drinking alcohol late into the evening, or dealing with an illness like the flu or a cold, to name just a few.3
Getting Ahead of Nocturnal Hypoglycemia
With the direction of your healthcare provider, you can put together a plan to help you avoid nocturnal hypoglycemia.
Some ideas for preventing low blood sugar overnight can include reducing your post-dinner or bedtime basal insulin after you exercise or adjusting your overall insulin doses with the help of your doctor. Staying consistent with the meals and snacks you eat in the evening and around bedtime may also help you avoid low blood sugar overnight.10
If you or your loved one wakes up with nocturnal hypoglycemia, it’s important to treat it with a quick source of sugar like hard candy, fruit juice, or glucose paste or tablets. It may also be necessary to eat a meal before heading back to sleep. If the person cannot be woken up, immediately call 911 or administer an emergency glucagon kit.3 All that said, make sure to first discuss with your doctor an action plan if you or your loved one experience a nighttime low.
How Dexcom G6 Can Help Reduce Nocturnal Hypoglycemia
One of the best ways to determine if you’re experiencing nighttime hypos and gain insight into why they might be occurring is by using a continuous glucose monitoring (CGM) system.2
If you’re not using a CGM system, you may need to check your glucose before bed, in the middle of the night, and once again in the morning over several nights to track changes that happen while you sleep.11 This can be very disruptive and leave you feeling exhausted the next day.
A CGM system like Dexcom G6 continuously monitors your glucose levels even when you sleep. The Dexcom G6 sensor and transmitter can be worn on the body 24/7. The transmitter sends glucose data to your receiver or compatible smart device* up to every 5 minutes. This makes it easy to check on your own or your loved one’s glucose levels at a glance before bed and in the morning.†
Imagine checking your phone before bed and seeing 4.1 mmol/L with a steady arrow to the right. You’re feeling pretty good about your sleep, right? Now imagine the same situation, but you see two arrows pointing down. This extra information from the trend arrows within the Dexcom G6 app can be crucial when making decisions before heading to bed. The arrows can help you make better informed decisions at night or in the morning to help you stay in your target range.
The Dexcom G6 can also provide a predictive Urgent Low Soon alert which can notify you if your glucose levels are quickly dropping and you are likely to approach hypoglycemia (below 3.1 mmol/L) within the next 20 minutes. This allows you to take proactive action to prevent the nighttime hypo. Dexcom G6 also has a built-in alarm that will tell you when you or your loved one are at or below a serious low of 3.1 mmol/L.‡ Using the Dexcom G6 predictive Urgent Low Soon alert is associated with a notable reduction in hypoglycemia.12,13
Can I view nighttime hypo trends with Dexcom?
Understanding how your glucose levels are fluctuating, and when, can help you and your healthcare provider get a better idea of how to prevent lows. Dexcom Clarity is an app you can use on your desktop or device that gives you a dashboard view of your historical glucose data from your Dexcom G6, all in one place.
One of the features of Dexcom Clarity that can help you pinpoint when or why nighttime hypos occur is the Trends reports. The Trends report gives you a visualization of how your glucose levels change over time. It uses colourful bars to indicate which parts of the day tend to be high or low, including how frequently it’s happening. This can help you see if you've been experiencing nighttime hypos and at what time of the night they are happening. You can then use this information to reflect on what might have caused you to go low.
You can share access to information in your Dexcom Clarity reports with your healthcare provider, giving them deeper insights into your glucose levels at night.§ Armed with this information, you can better collaborate on a strategy to reduce the possibility of nocturnal hypoglycemia.
Helping Your Loved One Prevent Nocturnal Hypoglycemia
If your loved one is living with diabetes and you’re looking for ways to actively support their diabetes management, there’s the Dexcom Follow app. This app allows you to receive glucose data remotely from your loved one’s Dexcom G6 transmitter and view it on your compatible smart device.* || This can help partners, caregivers, and parents sleep with a little extra peace of mind as they can get crucial alerts if a loved one is approaching hypoglycemia while they sleep.
Unlike a flash glucose monitoring (FGM) system like FreeStyle Libre 2 (which requires you to scan your device) or a fingerstick, you don’t need to disturb your loved one while they sleep to check their glucose levels when using Dexcom G6. As long as they stay in range, they can sleep soundly while you keep an eye on their glucose levels on your phone in another room.
Sharing glucose data with a follower via Dexcom Follow has also been shown to benefit the Dexcom G6 user. When Dexcom G6 users have a trusted follower, they feel more confident about avoiding hypoglycemia, have reduced distress related to diabetes, and see a significant improvement in the quality of their sleep.14
Get a Better Night’s Sleep with Dexcom G6
With Dexcom G6, your CGM system can help let you know if you’re at risk of a nighttime hypo in real time and help you understand where your glucose levels are and where they’re heading before bed so that you can take steps to prevent it. Dexcom CGM use has been proven to help reduce the number of nighttime hypo events.15
Talk to your healthcare provider about Dexcom G6 to see if a CGM system is the right diabetes management tool for you. If you need support with insurance coverage, you can learn more about the options available or contact us here.
*For a list of compatible smart devices, please visit
† If your glucose alerts and readings from the 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).
§ An internet connection is required to send data to Dexcom Clarity.
|| Requires the Follow App and an internet connection. Followers should always confirm readings on the Dexcom G6 App or Receiver before making treatment decisions.
1 Imran AS, et. al. Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada: Targets for Glycemic Control. Can J Diabetes 2018:42(S42–S46). doi: 10.1016/j.jcjd.2017.10.030
2 Nocturnal Hypoglycemia. MyHealth Alberta. Updated July 28, 2021. Accessed September 19, 2022.
3 Hypoglycemia: Nocturnal. Johns Hopkins Medicine. Accessed September 19, 2022.
4 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
5 Type 1 diabetes. Diabetes Canada. Accessed September, 19, 2022.
6 Getting started with insulin. Diabetes Canada. Accessed September 19, 2022.
7 Hypoglycemia. Mayo Clinic. Updated May 04, 2022. Accessed September 19, 2022.
8 Blood Sugar and Exercise. American Diabetes Association. Accessed September 19, 2022.
9 Hypoglycemia. Diabetes Canada. Accessed December 6, 2022.
10 Avoiding Nighttime Hypoglycemia. Joslin Diabetes. Accessed September 19, 2022.
11 Nocturnal Hypoglycemia. Updated June 10, 2022. Accessed September 19, 2022.
12 Puhr S, et al. Real-World Hypoglycemia Avoidance with a Continuous Glucose Monitoring System's Predictive Low Glucose Alert. Diabetes Technol Ther. 2019;21(4):155-158. doi:10.1089/dia.2018.0359
13 Puhr S, et al. Real-World Hypoglycemia Avoidance With a Predictive Low Glucose Alert Does Not Depend on Frequent Screen Views. J Diabetes Sci Technol. 2020;14(1):83-86. doi:10.1177/1932296819840691
14 Polonsky W, et al. Impact of Real-Time Continuous Glucose Monitoring Data Sharing on Quality of Life and Health Outcomes in Adults with Type 1 Diabetes. Diabetes Technology & Therapeutics. 2020; 23(4). doi: 10.1089/dia.2020.0466
15 Heinemann L, et al. Real-time continuous glucose monitoring in adults with type 1 diabetes and impaired hypoglycaemia awareness or severe hypoglycaemia treated with multiple daily insulin injections (HypoDE): a multicentre, randomised controlled trial. Lancet. 2018;391(10128):1367-1377. doi:10.1016/S0140-6736(18)30297-6

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