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Low blood sugar (hypoglycemia) associated with diabetes

Scientific support: Andreas Vosseler M.A.

Hypoglycemia causes the blood sugar level to drop below 70 mg/dl (3.9 mmol/l). Low blood sugar levels can occur in people with diabetes who inject insulin or take certain blood sugar-lowering tablets – for example, sulfonylureas. Severe hypoglycemia can lead to unconsciousness and is life-threatening.

Symptoms of low blood sugar levels may include sweating, shivering, restlessness, or pallor of the face. The causes of low blood sugar levels may be: Too much insulin or blood sugar-lowering tablets, unusual physical activity, not enough food, increased alcohol consumption. The blood sugar level rises again as soon as something containing sugar is eaten or drunk.

Hypoglycemia is the medical term for low blood sugar levels and is colloquially referred to as “hypo”.

A slightly elevated blood sugar level is comparatively common in people with type 1 diabetes. If affected individuals notice the signs early and are able to stop the drop in sugar levels by eating carbohydrates (for example, fruit juice), low blood sugar can usually be well controlled.

1. What is low blood sugar?

Low blood sugar (hypoglycemia) is when the blood sugar falls to low levels, causing symptoms such as sweating, shivering, feeling of hunger, and even impaired consciousness. There is no fixed threshold at which problems develop. According to the definition of the American Diabetes Association (ADA), low blood sugar occurs at levels below 70 mg/dl (3.9 mmol/l). However, low blood sugar levels can also become apparent at an earlier point or not before levels have dropped to lower values.

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2. Symptoms: How do I recognize low blood sugar levels?

The symptoms associated with low blood sugar can vary greatly from person to person. The most common symptoms are:

  • Shivering
  • Sweating
  • Feeling of hunger
  • Palpitations
  • Confusion, disorientation
  • Pallor of the face
  • Speech and vision impairment

Very low blood sugar levels may lead to unconsciousness and cramps.

Good to know:

You are not sure if it is hyperglycemia or hypoglycemia? Watch our video on acute emergencies in diabetes.

(This video is available with English subtitles.)

3. Immediate action: What helps in the event of low blood sugar levels?

In the event of a low blood sugar level, people with diabetes should immediately consume carbohydrates that enter rapidly enter the bloodstream.

When blood sugar levels are low, sugar-containing drinks such as fruit juice or lemonade can be taken. Dextrose tablets, gummy bears or a ripe banana also work quickly and cause blood sugar to rise again.

Foods with a high fat content, for example, chocolate, are not suitable as a rapid countermeasure in the event of low blood sugar levels. The high fat content delays the carbohydrates entering the bloodstream.

Depending on the severity of low blood sugar levels, 10 to 30 grams of carbohydrates should be taken. Close monitoring of the blood sugar levels is then necessary to prevent a further drop in blood sugar.

After consuming fast-acting carbohydrates, slow-acting carbohydrates that enter the bloodstream slowly, such as a slice of bread or a granola bar, can be eaten as a supplement. This can help maintain the blood sugar levels stable in the long term.

Good to know:

In the event of low blood sugar levels, eat something as soon as possible – then measure blood sugar levels.

In the event of unconsciousness

Under no circumstances should anything be poured into someone's mouth if that person is unconscious. Such persons are at risk of choking. Call the emergency services (112) and put the person to the recovery position.The emergency services can administer a glucose solution directly into the vein to help re-stabilize the blood sugar level. If possible, a glucagon injection or glucagon nasal spray may be used.

4. Glucagon injection and nasal spray

In the event of severely low blood sugar levels, a glucagon injection or glucagon nasal spray may be used – even if the patient is unconscious. However, this may only be done if high blood sugar levels can be ruled out. In case of unconsciousness, the emergency services should always be notified.

The hormone glucagon triggers the release of sugar (glucose) from the liver into the bloodstream, so that the blood sugar level rises. However, these measures do not work in case of increased physical activity or alcohol consumption shortly beforehand. In the latter case, the liver is too busy breaking down alcohol, while shortly after intense sports sessions, the liver works to replenish glycogen stores (glycogen = storage form of sugar). In these situations, sugar-containing drinks or foods should be taken if possible. Otherwise, the emergency medical services must be called immediately.



Glucagon injection

Glucagon nasal spray

  1. Remove the caps from the needle and vial. Take the injection containing the solution and inject it into the vial containing the glucagon powder.
  2. Then gently move the vial back and forth a few times until the powder has dissolved in the liquid. Do not remove the syringe from the vial during this stage.
  3. Pull the syringe plunger upwards to draw up the liquid.
  4. Pierce the skin on the upper leg, belly or upper leg with the needle.
  5. Inject the liquid.
  1. Do not test before use (single dose that cannot be reused). The spray can also be used if the nose is blocked. Application in adults, adolescents, and children over the age of 4.
  2. Remove the foil.
  3. Take the single-dose container between 2 fingers. Insert the tip into one of the nostrils until the fingers touch the outside of the nose.
  4. Push the plunger in as far as it will go until the green line is no longer visible.



After using a glucagon injection or glucagon nasal spray:

  • Once the person has regained consciousness, he or she should take something containing sugar to prevent recurrent hypoglycemia.
  • If the injection is still ineffective after 10 minutes, an emergency service must administer glucose via a vein.
  • Even hours later, blood sugar can drop again. For this reason, monitoring in a clinic is recommended.


It is useful to familiarize those around people with diabetes about the use of the glucagon injection or glucagon nasal spray. This will allow them to act properly in an emergency.

5. First aid protocol for low blood sugar levels

Good to know:

In case of extreme variations in blood sugar levels, continuous glucose monitoring (CGM) systems may display a delayed value. Therefore, blood sugar measurement using blood on the finger pulp is useful – especially if the blood sugar level drops rapidly or rises rapidly.

6. What are the causes of low blood sugar levels?

Low blood sugar levels may have a number of causes:

  • Insufficient carbohydrate intake: For example, because a meal was skipped or a meal had fewer carbohydrates than expected.
  • Exercise and sports: The body’s energy requirement increases during physical activity – especially during prolonged exercise such as a walk, a bike ride or even during housework. Furthermore, the body continues to burn additional calories for a long period after exercise, meaning that low blood sugar can develop hours later.
  • Insulin overdose: This can happen if more carbohydrates were taken into account for a meal than necessary and consequently too much insulin was injected. Low blood sugar levels can also be caused by change of insulin preparation or injection of insulin too long before eating.
  • Insulin accidentally injected into the muscle: This causes the effects of insulin to begin more rapidly. This can result in low blood sugar when carbohydrates are not eaten in time.
  • The use of certain blood sugar-lowering tablets (for example, sulfonylureas).
  • Alcohol: The blood sugar level can fall after drinking beer, wine, etc. Low blood sugar levels while sleeping can occur more easily after drinking alcohol at night.
  • Improved insulin absorption: When exposed to heat, e.g., when sunbathing, insulin enters the bloodstream more rapidly.
  • Improved insulin efficacy: Less insulin may be needed during the early stages of pregnancy or after weight loss.

Good to know:

Especially in cases of long-term diabetes and regular low blood sugar, the typical symptoms may only appear at very low blood sugar levels or at later and later points. This is also referred to as impaired awareness of low blood sugar levels. In this case, hypo awareness training can help raise the perception threshold again. Talk to your diabetes team to learn more about this training.

7. What helps combat nightly low blood sugar levels?

The following tips can help combat nightly low blood sugar levels:

  • Go to bed with a slightly elevated blood glucose level.
  • Eat long-acting carbohydrates during the evening meal or just before bedtime (for example, wholegrain products).
  • Carefully correct elevated blood sugar levels in the evening.
  • Reduce or completely avoid alcohol consumption in the evening.
  • Avoid sports in the late evening.
  • Change the insulin dosage (only after consulting your doctor).
  • Adjust the insulin therapy (only after consulting your doctor).
  • Use CGM (continuous glucose monitoring) with alarm function.

If someone suspects a drop in blood sugar levels during the night, they should test their blood sugar levels between 2 and 3 am. CGM systems – especially those with an alarm function – can also help detect nightly low blood sugar levels.

Good to know:

If low blood sugar goes unnoticed while sleeping, it can result in fatigue, exhaustion, or a headache the following morning. If nightly blood sugar levels are low, the body independently counter-regulates as a result of stress hormones. This can stimulate the release of sugar from the liver into the blood. Although rare, the morning blood sugar can be very high following a nighttime episode of low blood sugar. This is known as the Somogyi effect. A low blood sugar level after waking up can also be a sign of nocturnal low blood sugar.

8. Low blood sugar episode when driving

Concentration is needed when driving. Low blood sugar levels are especially dangerous when at the wheel. Especially if you have a preexisting susceptibility to hypoglycemia, you should take a few precautions if you plan to drive.

  • Test blood sugar levels before driving. If the levels are too low, eat fast-acting carbohydrates. Only get into the car once the levels are normal.
  • Document blood sugar levels and treatment measures.
  • Keep fast-acting carbohydrates in the car for emergencies. If you notice the initial symptoms of low blood sugar, stop the car and eat something. Only continue your journey once levels have returned to normal.

9. How can low blood sugar levels be prevented?

If noticed, low blood sugar levels can be rapidly counteracted with drinks or foods that are rich in carbohydrates. Therefore, foods rich in sugar should always be ready at hand. Furthermore, diabetes-specific devices can be packed in an “emergency set”. Depending on the diabetes therapy, the set should include glucagon nasal spray, a substitute insulin ampoule or insulin pen in addition to glucose.

10. Can people without diabetes have low blood sugar levels?

Even without diabetes, low blood sugar levels can result in the typical symptoms of hypoglycemia such as shivering, pallor of the face, palpitations or feeling of hunger, although only in rare cases. Particularly slender persons report such symptoms frequently. However, low blood sugar levels are not a sign of diabetes.

Normally, the metabolically healthy body knows how to help itself when blood sugar is low. A drop in blood sugar causes the liver to release sugar reserves that are stored there for precisely this purpose.

In the following situations, people without diabetes may also notice symptoms of a low blood sugar level:

  • During fasting
  • After consuming alcohol or coffee
  • During or after long-lasting, exhausting sports sessions
  • After eating meals rich in carbohydrates, which cause blood sugar levels to rise rapidly and trigger a high release of insulin

In most cases, the symptoms of low blood sugar are harmless in people not suffering from diabetes. Sugar-containing drinks or foods cause blood sugar levels to rise again. But be careful: If too many carbohydrates are taken as a countermeasure, the body will in turn probably release too much insulin. This may then again result in signs of low blood sugar.


Ensure that you take slow-acting carbohydrates. These include complex, high fiber carbohydrates (for example, wholegrain bread or granola bars) or carbohydrates consumed along with protein- and/or fat-containing foods (such as rice with vegetables and fish). This prevents hunger attacks and low blood sugar levels.

Symptoms of low blood sugar levels that occur more frequently in people without diabetes may indicate other diseases. Causes may be, for example:

  • Malnutrition
  • Lack of hormones, especially adrenal insufficiency
  • Tumor on the pancreas that causes high insulin production (insulinoma)

Talk to your doctor when you suffer from frequently recurring low blood sugar levels.


Ärzteblatt online: Hypoglykämie: Gucagon wirkt als Nasenspray zuverlässig. Artikel vom 30.05.2022
ÄrzteZeitung online: Krankhafte Hypoglyklämien gibt es auch bei Menschen ohne Diabetes (Letzter Abruf: 05.04.2023)
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As of: 05.04.2023