Home > Health & Wellness > Health Library > Diabetes-Related High and Low Blood Sugar Levels
diabetes, you may have high blood sugar levels
(hyperglycemia) or low blood sugar levels (hypoglycemia)
from time to time. A cold, the flu, or other sudden illness can cause high
blood sugar levels. You will learn to recognize the symptoms and distinguish
between high and low blood sugar levels.
Insulin and some types of
diabetes medicines can cause low blood sugar levels.
Learn how to recognize and manage high and low blood sugar levels
to help you avoid levels that can lead to medical emergencies, such as
diabetic ketoacidosis or
dehydration from high blood sugar levels or
loss of consciousness from severe low blood sugar
levels. Most high or low blood sugar problems can be managed at home by
following your doctor's instructions.
You can help avoid blood sugar problems by following your doctor's
instructions on the use of insulin or diabetes medicines, diet, and exercise.
Home blood sugar testing will help you determine
whether your blood sugar is within your
target range. If you have had very low blood sugar,
you may be tempted to let your sugar level run high so that you do not have
another low blood sugar problem. But it is most important that you keep your
blood sugar in your target range. You can do this by following your treatment
plan and checking your blood sugar regularly.
Sometimes a pregnant woman can get diabetes during her pregnancy. This is called gestational diabetes. Blood sugar levels are checked regularly during the pregnancy to keep levels within a target range.
Children who have
diabetes need their parents' help to keep their blood sugar levels in a target
range and to exercise safely. Be sure that children learn the
symptoms of both
low blood sugar so they can tell others when they need help. There are many
support groups and diabetes education centers to help parents and children
understand about blood sugar, exercise, diet, and medicines.
especially may have a hard time keeping their blood sugar levels in control
because their bodies are growing and developing. Also, they want to be with
their friends and eat foods that may affect their blood sugar. Having diabetes
during the teenage years is not easy. But your teen is at an excellent age to
understand the disease and its treatment and to take over some of the
responsibilities of his or her care.
If your blood sugar level
reads too high or too low but you are feeling well, you may want to recheck
your sugar level or recalibrate your blood glucose meter. The problem may be
with either your blood sample or the machine.
High blood sugar occurs when the sugar (glucose) level in your blood
rises above your target range. Eating too many calories, missing medicines (insulin or
pills), or having an infection or illness, injury, surgery, or emotional stress
can cause your blood sugar to rise.
High blood sugar usually
develops slowly over a period of hours to days. But missing a dose of insulin
can cause a rapid rise in blood sugar levels. Blood sugar levels just above
your target range may make you feel tired and thirsty. If your blood sugar
level stays higher than your target range for weeks, your body will adjust to that level,
and you may not have as many
symptoms of high blood sugar.
don't monitor your blood sugar regularly or you don't notice the symptoms of
high blood sugar, you usually will have time to treat high blood sugar so that
you can prevent high blood sugar emergencies. Three things can help you prevent
high blood sugar problems:
Complications of high blood sugar can cause serious
problems, including coma and death. Over time, high blood sugar can damage your
eyes, heart, kidneys, blood vessels, and nerves.
blood sugar occurs when the sugar (glucose) level in your blood drops below
what your body needs. Not eating enough food or skipping meals, taking too much
medicine (insulin or pills), exercising more than usual, or taking certain
medicines that lower blood sugar can cause your blood
sugar to drop rapidly. Do not drink alcohol if you have problems recognizing the early signs of low blood sugar.
People who lose weight or develop kidney
problems may not need as much insulin or other medicines as they did before
they lost the weight or developed kidney problems. Their blood sugar may drop
too low. Be sure to check your blood sugar often when your body goes
When your blood sugar level drops below 70
milligrams per deciliter (mg/dL), you will usually
have symptoms of low blood sugar. This can develop quickly,
in 10 to 15 minutes.
You may have symptoms of low blood sugar if your blood sugar
drops from a high level to a lower level. For example, if your blood sugar
level has been higher than 300 mg/dL for a week or so and the level drops
suddenly to 100 mg/dL, you may have symptoms of low blood sugar even though
your blood sugar is in the target range. But if you have had diabetes for many
years, you may not have symptoms of low blood sugar until your blood sugar
level is very low.
If your doctor thinks you have low blood sugar
levels but you are not having symptoms, he or she may ask you to check your
blood sugar more often. Your doctor may ask you to check your blood sugar in
the middle of the night or to do a 3-day test using a continuous glucose monitor.
Check your symptoms to decide if and when
you should see a doctor.
Health Tools help you make wise health decisions or take action to improve your health.
Many things can affect how your body responds to a symptom and what kind
of care you may need. These include:
Symptoms of diabetic ketoacidosis may
Early symptoms of low blood sugar may
If blood sugar continues to drop, you may start to have more
Severe dehydration means:
Moderate dehydration means:
Mild dehydration means:
Severe dehydration means:
You can get dehydrated when
you lose a lot of fluids because of problems like vomiting or fever.
Symptoms of dehydration can range from mild to severe. For
Symptoms of serious illness in a baby
may include the following:
You have answered all the questions. Based on your answers, you may be
able to take care of this problem at home.
Symptoms of serious illness may
Symptoms of infection may
Based on your answers, you may need care soon. The
problem probably will not get better without medical care.
Here is what you can do to treat low blood sugar. If at any point during these steps you think you are getting
worse, seek care immediately.
Based on your answers, the problem may not improve without medical
Based on your answers, you may need care right away. The problem is likely to get worse without medical care.
Based on your answers, you need
Call911or other emergency services now.
You can test urine for ketones at home using special tablets or test strips. Ketones are
substances made by the body when it burns fat instead of sugar. They are a sign
that your blood sugar is out of control.
To do the test:
When you have diabetes, whether it
type 1 diabetes,
type 2 diabetes, or
gestational diabetes, one of the most important skills
you will learn is how to manage your blood sugar level.
Following your doctor's
instructions on the use of
insulin or diabetes medicines, diet, and exercise will
help you avoid blood sugar problems. You will learn to recognize the symptoms
and distinguish between high and low blood sugar levels. It may be hard
for a parent of a young child to distinguish the
difference between high and low blood sugar symptoms in a child.
When you have learned to recognize high or low blood sugar
levels, you can take the appropriate steps to bring your blood sugar level back
target blood sugar levels.
People who keep
their blood sugar levels under control with diet, exercise, or oral diabetes
medicines are less likely to have problems with high or low blood sugar
levels. Do not drink alcohol if you have problems recognizing the early signs of low blood sugar.
sure to know the steps for dealing with high blood sugar and how fast your insulin medicine will work to bring your blood sugar
down. Some insulins work very fast while regular insulin takes a little longer
to bring the sugar level down. Knowing how fast your insulin works will keep
you from using too much too quickly.
you have diabetes and can have low blood sugar levels, you need to keep some
type of food with you at all times that can quickly raise your blood sugar
level. These should be quick-sugar foods (about 15 grams of carbohydrate). Be sure to check
your blood sugar level again 15 minutes after eating a quick-sugar
(carbohydrate) food to make sure your level is getting back to your target
range. If you continue to have low blood sugar, take another 15 grams of carbohydrate. When your blood sugar gets to 70 mg/dL or higher, you can eat your normal meals and snacks. Eat a small snack if your next meal or snack is more than a few hours away.
It is important to know that sugar foods like a candy bar
or ice cream do not help raise low blood sugar levels quickly, because these
foods also have fat and protein. So the body can't use the sugar
(carbohydrate) in these foods quickly to raise the blood sugar level.
You can get low blood sugar from using too much insulin or from other medicines you take.
Parents need to help their child learn to treat a low blood sugar level.
Pregnant women who have gestational diabetes also need to know how to deal with a low blood sugar level.
Since low blood sugar levels can quickly become a medical
emergency, be sure to wear medical identification, such as a
medical alert bracelet, to let people know you have diabetes so they can get
help for you.
If you have severe symptoms of low blood sugar,
someone else may need to give you a
shot of glucagon. If this occurs, be sure to call your doctor immediately to let
him or her know this has happened.
Call your doctor if any of the following occur during home
Although high blood sugar (hyperglycemia)
and low blood sugar (hypoglycemia) have very different symptoms and treatments,
they are both caused by blood sugar and insulin imbalances. The steps you take
to control your blood sugar level will help prevent both high and low blood
Be sure to have identification that says you have diabetes, such as a
medical alert bracelet, with you at all times. This
will help other people take steps to care for you if you are not able tell them
about your medical condition.
You can take steps to prevent high
and low blood sugar emergencies.
home blood sugar tests to determine whether your blood
sugar is in your
target range. Work with your doctor to set your
individual treatment goals. If you can consistently maintain this level of
control, you will have very few blood sugar level emergencies.
Parents can help their child learn how to prevent low blood sugar levels and high blood sugar levels.
No matter how skilled you are at
monitoring and controlling your blood sugar levels, you are still at risk for
high or low blood sugar levels that are brought on by stressful situations.
Stress can affect your body's blood sugar levels in two ways:
Stress can be both mental and physical. Some examples of
stress include an illness, a bad day at work, and a tough problem at home. When
you are under stress, your blood sugar levels change. For more information, see
You can keep your
blood sugar levels under control when you exercise, so that you do not become
too hungry or make your blood sugar level drop. There are two ways to keep your
blood sugar levels under control:
quick-sugar food with you during exercise in case your
blood sugar level drops low.
Your doctor may recommend that you get
vaccinations, such as a
flu(What is a PDF document?) vaccine
vaccine, to prevent you from those illnesses.
The American Diabetes
Association has a lot of information on diabetes and can link you to support
groups. For more information, call 1-800-DIABETES (1-800-342-2383) or see the
organization's website: www.diabetes.org/home.
To prepare for your appointment, see the topic Making the Most of Your Appointment.
You can help your
doctor treat your condition by being prepared to answer the following
Be sure to take your daily blood sugar (glucose) monitoring
logbook to your appointment. If you have specific records of your high(What is a PDF document?) and low(What is a PDF document?) blood sugar
problems, be sure to take those records.
Parents will also need to keep records of their child's high or low(What is a PDF document?) blood sugar problems to share with their child's doctor.
American Diabetes Association (2011). Carbs: Fast! Available online:
Warshaw H, Kulkarni K (2011). The Complete Guide to Carb Counting, 3rd ed. Alexandria, VA: American Diabetes Association.
American Diabetes Association (2010). Hypoglycemia. Available online: http://www.diabetes.org/living-with-diabetes/parents-and-kids/planet-d/new-to-diabetes/hypoglycemia.html.
Other Works Consulted
American Diabetes Association (2015). Standards of medical care in diabetes—2015. Diabetes Care, 38(Suppl 1): S1–S93.
ByHealthwise StaffPrimary Medical ReviewerWilliam H. Blahd, Jr., MD, FACEP - Emergency MedicineKathleen Romito, MD - Family MedicineSpecialist Medical ReviewerH. Michael O'Connor, MD - Emergency Medicine
Current as ofJanuary 28, 2015
Current as of:
January 28, 2015
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & Kathleen Romito, MD - Family Medicine & H. Michael O'Connor, MD - Emergency Medicine
How this information was developed to help you make better health decisions.
To learn more, visit Healthwise.org
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