Nocturnal Hypoglycemia: Signs, Prevention and Treatment

If you are diabetic, you probably know that the main aim of your treatment is to achieve glycemic control and keep your blood sugar levels within a target range. 

You don’t want your blood sugar to get too high (hyperglycemia), but you also do not want it to become too low (hypoglycemia) because this can lead to serious consequences like seizures and unconsciousness. 

During the day, you are generally alert. It is easier to maintain glycemic control, detect hypoglycemia and correct your blood sugar when necessary. 

But what happens when your blood sugar drops at night while you are asleep? 

This article discusses the concept of nighttime hypoglycemia and tells you everything you need to know about its causes, symptoms, prevention, and treatment. 

What is nocturnal hypoglycemia?

The word ‘nocturnal’ refers to something that takes place at night. And the word ‘hypoglycemia’ is the medical term for low blood sugar. 

Put the meaning of these two words together, and it becomes obvious that the term “nocturnal hypoglycemia” refers to low blood sugar levels that occur at night, usually when a person is asleep. 

Hypoglycemia is defined as blood glucose levels below 70mg/dl. It can be mild, moderate, or severe.  Severe hypoglycemia is when blood sugar is so low that a person experiences mental or physical impairment and requires help from others to recover. Blood glucose is often below 40 mg/dL in this case. 

According to a 2017 study, more than half of all episodes of severe hypoglycemia – which can be fatal – occur at night.

Both daytime and nighttime hypoglycemia are more common in diabetics, mainly because hypoglycemia is a side effect of blood-sugar-lowering drugs like insulin. However, it is important to know that hypoglycemia can also occur in non-diabetic people. We’ll discuss more on the hows and whys of this later. 

Is nocturnal hypoglycemia dangerous?

Hypoglycemia is potentially fatal, no matter what time of the day it occurs. However, nocturnal hypoglycemia is considered to be particularly dangerous. 

This is because, during the daytime, you are more likely to be monitoring your blood sugar frequently. Also, since you are awake, you are more likely to be aware of any symptoms of hypoglycemia. And, if hypoglycemia is detected, you can quickly correct it. 

At night, on the other hand, you are likely to be asleep and unaware of symptoms. As such, your glucose levels may drop to severe levels without being detected and corrected early.  

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What causes nocturnal hypoglycemia? 

Nocturnal hypoglycemia is a common condition in people with type 1 diabetes and those with advanced type 2 diabetes who are being treated with insulin. 

A 2018 study included a total of 679 participants – 321 of them had type 1 diabetes and 293 had type 2 diabetes. 54.0% of those with type 1 diabetes and 27.4% of those with type 2 diabetes had at least one episode of nocturnal hypoglycemia during the study period. 

In diabetics, the most common cause of hypoglycemia is blood sugar-lowering medications, particularly insulin and sulfonylureas. Here are some scenarios that can increase your risk of experiencing nocturnal hypoglycemia while on diabetic drugs: 

  • Not eating enough food after taking your usual dose of insulin at night. 
  • Skipping dinner.
  • Using a higher nighttime dose of insulin – or oral diabetic drugs – than what is prescribed.
  • Strenuous exercise before bed.
  • Consuming alcohol before bed.

As mentioned earlier, nocturnal hypoglycemia can occur in people without diabetes. However, it is considered a rare condition. Here are some common causes: 

  • Medications: Beta-blockers like atenolol and antibiotics such as trimethoprim-sulfamethoxazole can lower your blood sugar. 
  • Alcohol: Drinking alcohol can affect your normal blood sugar regulation. Alcohol reduces your body’s glycogen stores. It also reduces your liver’s ability to use gluconeogenesis to make new glucose molecules. As such, drinking alcohol at night could result in nocturnal hypoglycemia.
  • Medical conditions: Several medical conditions can put you at risk of nocturnal hypoglycemia. These include liver disease, kidney disease, and hypothyroidism. 

Signs of low blood sugar levels at night

Because hypoglycemia during sleep is potentially dangerous, you, your partner, roommates, and family members must be aware of the warning signs. That way, intervention can happen quickly. 

Generally, hypoglycemia can cause signs and symptoms such as: 

  • Tremors or shaking
  • Restlessness 
  • Sudden changes in breathing pattern 
  • Feeling your heart race
  • Hunger 
  • Lightheadedness
  • Breaking out in a sweat

Since nocturnal hypoglycemia occurs at night, you may not be alert enough to notice the above symptoms. Here are some more specific warning signs that you should be aware of:  

  • Restless and uncomfortable sleep
  • Having nightmares 
  • Damp sheets or pajamas (from night sweats)
  • Feeling unrested, unfocused, or moody when you wake up
  • Having a headache when you wake
  • Having an unusually high glucose level when you wake up

When you have a restless sleep or a low blood sugar nightmare, you may suddenly wake up and become aware that you are having a hypoglycemic episode. 

However, most of the above symptoms are only noticed after you wake up in the morning, indicating that you may have had an episode of hypoglycemia while you were asleep.  

You are even more likely to sleep through an episode of nighttime hypoglycemia – and go into severe hypoglycemia – if you have a condition called hypoglycemia unawareness

Hypoglycemia unawareness is when a person has low blood sugar but does not notice any symptoms. Why this happens in some people is not fully understood. However, some risk factors have been identified: 

  • Having long-standing diabetes
  • Having type 1 diabetes
  • Being older than 65 years 
  • Having episodes of low blood sugar frequently 
  • Using medications like beta blockers

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How to prevent low blood sugar at night

It is not always possible to totally avoid having episodes of low blood sugar at night. However, you can reduce your risk of experiencing nighttime hypoglycemia using the following tactics: 

1) Check your blood sugar during the night

Checking your blood sugar right before you sleep can give you an idea of your sugar levels at night. You can also try to wake up and check your blood sugar from around 2 a.m. to 3 a.m.

If you notice that your blood sugar is on the low side but not at a hypoglycemic level (70mg/dl to 100mg/dl), you can speak with your healthcare provider about how to achieve better glycemic control. 

If your blood sugar is at hypoglycemic levels (less than 70g/dl), you must correct it as soon as possible. We discuss more about that later. 

You can also check your blood sugar when you wake up. Having a higher-than-usual glucose reading in the morning may indicate that your body is rebounding from an episode of low blood sugar that occurred at night. 

2) Consider continuous glucose monitoring

A continuous glucose monitor (CGM) measures your blood sugar levels every few minutes. These devices are particularly helpful for detecting and preventing nighttime hypoglycemia

With a CGM, you get a better view of your blood sugar trends than with a standard glucometer. This could make it easier to identify problems and make adjustments to prevent nighttime dips in your blood sugar. 

Also, CGMs are designed to notify you when your blood sugar falls below a set level. The alarms are loud enough to wake you up from sleep when your blood sugar is low, allowing you to correct episodes quickly.  

3) Avoiding strenuous exercise at night 

Regular exercise is important, but strenuous exercise right before you sleep is not advisable because it can lower your blood sugar

When you exercise, your muscles use glucose as fuel to power the activity. Plus, the effectiveness of insulin increases after exercise, which means that glucose is taken up more quickly from your blood and into your body’s cells. This is why exercising can cause dips in blood glucose. 

If you experience nocturnal hypoglycemia, consider exercising during the daytime instead of at night. If your schedule only allows you to exercise at night, consider eating carbohydrate-filled snacks before and/or after exercising. 

Check your blood sugar levels before and after exercise to see how the activity affects your blood sugar. 

You can also speak with your healthcare provider about adjusting your nightly insulin dose to accommodate the increase in physical activity. 

4) Avoid skipping evening meals and try snacks

When you sleep, your body uses glucose to power vital functions like breathing, digesting food, and pumping blood. By not giving your body the fuel it needs in the form of carbohydrates, you increase your risk of hypoglycemia.  This is why it is important to avoid skipping a meal that you would normally have at night. 

Eating a carbohydrate-rich snack before bed may also help if you frequently experience nocturnal hypoglycemia. 

If you want to drink alcohol at night, eating a snack can help counteract the effects and prevent dips in your blood sugar when you sleep. 

5) Adjust your insulin dose

If you’re taking insulin and frequently experience low blood sugar episodes at night, you need to speak to your healthcare provider about possibly adjusting your insulin regimen. Never adjust your dose of insulin – or other diabetic medications – without speaking to your healthcare provider. 

If you use fast-acting insulin, it is best to check your blood sugar levels before administering it because it reduces your blood sugar. quickly You may not need to administer it if your blood sugar is low enough. 

If you use an insulin pump, you can adjust the settings to lower your basal insulin delivery rate and avoid dips in your blood sugar while you are asleep. 

Treating nocturnal hypoglycemia

As mentioned earlier, it is not always possible to completely eliminate episodes of nocturnal hypoglycemia. Sometimes, nocturnal hypoglycemia can occur without known risk factors and despite lifestyle and medication changes. 

So it is important that you – and the people around you – are prepared to treat nocturnal hypoglycemia promptly when an episode occurs: 

Mild to moderate hypoglycemia

With mild to moderate hypoglycemia, you can usually help yourself, but you may need help from others if you feel dizzy or disoriented. 

You need to eat or drink something with fast-acting glucose immediately. Some examples are glucose paste or tablets, hard candy, and fruit juice. It is important to always keep these quick sources of glucose close by for emergencies. 

Once you have taken a fast-acting glucose source and you are fully awake, eat a meal rich in carbohydrates and check your blood sugar. 

Severe hypoglycemia

Severe hypoglycemia is a medical emergency. It can cause unconsciousness, convulsions, and make it difficult to swallow. In this case, you’ll need the assistance of the people around you to recover. 

You need something very fast-acting. As such, the best option is a glucagon injection. Glucagon is a hormone that stimulates your body to break down glycogen stores and release glucose. 

Speak to your doctor about having an emergency glucagon kit in your home. Ensure your roommates, coworkers, friends, and family know where the kit is and how to administer it. 

It is important to always inform your health provider after you experience nocturnal hypoglycemia. That way, you can discuss what may have triggered the episode and find strategies to prevent it from happening again. 


Nocturnal hypoglycemia is when your blood sugar drops below 70mg/dl at night. Because you are likely to be asleep and unaware of symptoms, it can be more deadly than daytime hypoglycemia. 

The keys to preventing nocturnal hypoglycemia are knowing the symptoms, understanding and avoiding the risk factors, and monitoring your blood sugar frequently. 

Always keep sources of fast-acting glucose nearby and make sure that those close to you know how to administer emergency treatment in case of a severe episode of nocturnal hypoglycemia.

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  1. Graveling AJ, Frier BM. The risks of nocturnal hypoglycaemia in insulin-treated diabetes. Diabetes Res Clin Pract. 2017 Nov;133:30-39.
  2. Siamashvili M, Davis HA, Davis SN. Nocturnal hypoglycemia in type 1 and type 2 diabetes: an update on prevalence, prevention, pathophysiology and patient awareness. Expert Rev Endocrinol Metab. 2021 Nov;16(6):281-293.
  3. Lamounier, R.N., Geloneze, B., Leite, S.O. et al. Hypoglycemia incidence and awareness among insulin-treated patients with diabetes: the HAT study in Brazil. Diabetol Metab Syndr 10, 83 (2018).
  4. Margaret Eckert-Norton, PhD, Susan Kirk, MD, Non-diabetic Hypoglycemia, The Journal of Clinical Endocrinology & Metabolism, Volume 98, Issue 10, 1 October 2013, Pages 39A–40A.

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