Low blood sugar
Hypoglycemia; Insulin shock; Insulin reaction; Diabetes - hypoglycemiaLow blood sugar is a condition that occurs when the body's blood sugar (glucose) decreases and is too low.
Blood sugar below 70 mg/dL (3.9 mmol/L) is considered low. Blood sugar at or below this level can be harmful.
The medical name of low blood sugar is hypoglycemia.
Causes
Insulin is a hormone made by the pancreas. Insulin is needed to move glucose into cells where it is stored or used for energy. Without enough insulin, glucose builds up in the blood instead of going into the cells. This leads to symptoms of diabetes.
Diabetes
Diabetes is a long-term (chronic) disease in which the body cannot regulate the amount of sugar in the blood.
Read Article Now Book Mark ArticleLow blood sugar occurs due to any of the following:
- Your body's glucose is used up too quickly
- Glucose production by the body is too low or it is released into the bloodstream too slowly
- Too much insulin is in the bloodstream
Low blood sugar is common in people with diabetes who are taking insulin or certain other medicines to control their diabetes. However, many other diabetes medicines do not cause low blood sugar.
Exercise can also lead to low blood sugar in people taking insulin to treat their diabetes.
Babies born to mothers with diabetes may have severe drops in blood sugar right after birth.
In people who do not have diabetes, low blood sugar may be caused by:
- Drinking alcohol
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Insulinoma, which is a rare tumor in the pancreas that produces too much insulin
Insulinoma
An insulinoma is a tumor in the pancreas that produces too much insulin.
Read Article Now Book Mark Article - Lack of a hormone, such as cortisol, growth hormone, or thyroid hormone
- Severe heart, kidney, or liver failure
- Infection that affects the whole body (sepsis)
Sepsis
Sepsis is an illness in which the body has a severe, inflammatory response to bacteria or other germs.
Read Article Now Book Mark Article - Some types of weight-loss surgery (usually 5 or more years after the surgery)
- Medicines not used to treat diabetes (certain antibiotics or heart medicines)
Symptoms
Symptoms you may have when your blood sugar gets too low include:
-
Double vision or blurry vision
Double vision
There are many types of eye problems and vision disturbances, such as: Halos Blurred vision (the loss of sharpness of vision and the inability to see...
Read Article Now Book Mark Article - Fast or pounding heartbeat
- Feeling cranky or acting aggressive
- Feeling nervous
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Headache
Headache
A headache is pain or discomfort in the head, scalp, or neck. Serious causes of headaches are rare. Most people with headaches can feel much better...
Read Article Now Book Mark Article - Hunger
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Seizures
Seizures
A seizure is the physical changes in behavior that occurs during an episode of specific types of abnormal electrical activity in the brain. The term ...
Read Article Now Book Mark Article - Shaking or trembling
- Sweating
- Tingling or numbness of the skin
- Tiredness or weakness
- Trouble sleeping
- Unclear thinking
In many people with diabetes, low blood sugar causes nearly the same symptoms every time it happens. Not everybody feels low blood sugar symptoms the same way.
Some symptoms, like hunger or sweating, occur when blood sugar is only slightly low. More severe symptoms, such as unclear thinking or seizure, may occur when the blood sugar is much lower (less than 54 mg/dL or 3.0 mmol/L).
Even if you do not have symptoms, your blood sugar could still be too low (called hypoglycemic unawareness). You may not even know you have low blood sugar until you faint, have a seizure, or go into a coma. If you have diabetes, ask your health care provider if wearing a continuous glucose monitor can help you detect when your blood sugar is getting too low to help prevent a medical emergency. Some continuous glucose monitors can alert you and other people that you designate when your blood sugar decreases below a set level.
Coma
Decreased alertness is a state of reduced awareness and is often a serious condition. A coma is the most severe state of decreased alertness from whi...
Read Article Now Book Mark ArticleIf you have diabetes, keeping good control of your blood sugar can help prevent low blood sugar. Talk to your provider if you're not sure about the causes and symptoms of low blood sugar.
Exams and Tests
When you have low blood sugar, the reading will be lower than 70 mg/dL (3.9 mmol/L) on your glucose monitor.
Your provider may ask you to wear a small monitor that measures your blood sugar every 5 minutes (continuous glucose monitor). The device is typically worn for 3 to 14 days. The data is downloaded to find out if you're having periods of low blood sugar that are going unnoticed.
If you're admitted to the hospital, you'll likely have blood samples taken from your vein to:
- Measure your blood sugar level
- Diagnose the cause of your low blood sugar (these tests need to be carefully timed related to low blood sugar to make an accurate diagnosis)
Treatment
The goal of treatment is to correct your low blood sugar level. It is also important to try and identify the reason why the blood sugar was low to prevent another low blood sugar episode from happening.
If you have diabetes, it is important that your provider teaches you how to treat yourself for low blood sugar. Treatment may include:
Treat yourself for low blood sugar
Low blood sugar is a condition that occurs when your blood sugar (glucose) is lower than normal. Low blood sugar may occur in people with diabetes w...
Read Article Now Book Mark Article- Drinking juice
- Eating food
- Taking glucose tablets
Or you may have been told to give yourself a shot of glucagon. This is a medicine that raises blood sugar.
If low blood sugar is caused by an insulinoma, surgery to remove the tumor will be recommended.
Insulinoma
An insulinoma is a tumor in the pancreas that produces too much insulin.
Read Article Now Book Mark ArticlePossible Complications
Severe low blood sugar is a medical emergency. It can cause seizures and brain damage. Severe low blood sugar that causes you to become unconscious is called hypoglycemic or insulin shock.
Even one episode of severe low blood sugar may make it less likely for you to have symptoms that allow you to recognize another episode of low blood sugar. Episodes of severe low blood sugar can make people afraid to take insulin as prescribed by their provider.
When to Contact a Medical Professional
If signs of low blood sugar do not improve after you have eaten a snack that has sugar:
- Get a ride to the emergency room. Do not drive yourself.
- Call 911 or the local emergency number
Get medical help right away for a person with diabetes or low blood sugar who:
- Becomes less alert
- Cannot be woken up
References
American Diabetes Association Professional Practice Committee. 6. Glycemic Goals and Hypoglycemia: Standards of Care in Diabetes-2024. Diabetes Care. 2024;47(Suppl 1):S111-S125. PMID: 38078586 pubmed.ncbi.nlm.nih.gov/38078586/.
Cryer PE, Arbeláez AM. Hypoglycemia. In: Melmed S, Auchus RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 38.
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Food and insulin release - illustration
Insulin is a hormone secreted by the pancreas in response to increased glucose levels in the blood.
Food and insulin release
illustration
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15/15 rule - illustration
To treat low blood sugar the 15/15 rule is usually applied. Eat 15 grams of carbohydrate and wait 15 minutes. The following foods will provide about 15 grams of carbohydrate; 3 glucose tablets; half a cup (4 ounces or 120 milliliters) of fruit juice or regular soda; 6 or 7 hard candies; or 1 tablespoon (15 grams) of sugar. After the carbohydrate is eaten, the person should wait about 15 minutes for the sugar to get into their blood. If the person does not feel better within 15 minutes, more carbohydrate can be consumed. Their blood sugar should be checked to make sure it has come within a safe range.
15/15 rule
illustration
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Low blood sugar symptoms - illustration
Symptoms such as weakness, feeling tired, shaking, sweating, headache, hunger, nervousness and irritability are signs that a persons blood sugar is getting dangerously low. A person showing any of these symptoms should check their blood sugar. If the level is low (70 mg/dL), a sugar-containing food should be eaten right away.
Low blood sugar symptoms
illustration
-
Food and insulin release - illustration
Insulin is a hormone secreted by the pancreas in response to increased glucose levels in the blood.
Food and insulin release
illustration
-
15/15 rule - illustration
To treat low blood sugar the 15/15 rule is usually applied. Eat 15 grams of carbohydrate and wait 15 minutes. The following foods will provide about 15 grams of carbohydrate; 3 glucose tablets; half a cup (4 ounces or 120 milliliters) of fruit juice or regular soda; 6 or 7 hard candies; or 1 tablespoon (15 grams) of sugar. After the carbohydrate is eaten, the person should wait about 15 minutes for the sugar to get into their blood. If the person does not feel better within 15 minutes, more carbohydrate can be consumed. Their blood sugar should be checked to make sure it has come within a safe range.
15/15 rule
illustration
-
Low blood sugar symptoms - illustration
Symptoms such as weakness, feeling tired, shaking, sweating, headache, hunger, nervousness and irritability are signs that a persons blood sugar is getting dangerously low. A person showing any of these symptoms should check their blood sugar. If the level is low (70 mg/dL), a sugar-containing food should be eaten right away.
Low blood sugar symptoms
illustration
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Review Date: 2/28/2024
Reviewed By: Sandeep K. Dhaliwal, MD, board-certified in Diabetes, Endocrinology, and Metabolism, Springfield, VA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.