What are the signs that your sugar is high

High blood sugar (hyperglycaemia) is where the level of sugar in your blood is too high. It mainly affects people with diabetes and can be serious if not treated.

Table of Contents Show

High blood sugar levels
Symptoms of high blood sugar
Causes of high blood sugar
How to lower your blood sugar
Non-urgent advice: Speak to your care team or GP surgery if:
Problems caused by high blood sugar
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Early signs and symptoms
Later signs and symptoms
When to see a doctor
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People with diabetes can also have blood sugar that's too low. This is called low blood sugar (hypoglycaemia).

High blood sugar levels

If you have diabetes, you can find out if your blood sugar level is high by having a blood sugar (blood glucose) test.

You may have regular tests by your care team or GP surgery, or you may have tests you can do at home.

Types of diabetes test and high blood sugar levels.Type of testHigh levelTest done by a health professional to check your blood sugar level over the last 2 or 3 months (HbA1c test)48 mmol/mol or over (6.5% if you're given a percentage)Test done by a health professional after not eating for a few hours (fasting glucose test)Over 7 mmol/LHome test done after waking up or before eatingOver 7 mmol/LHome test done at any other timeOver 11 mmol/L

Important

These blood sugar levels are a guide. Your levels may be different depending on your age and the type of diabetes you have. Check with your doctor or care team.

Symptoms of high blood sugar

Symptoms of high blood sugar usually come on gradually and may only start when your blood sugar level gets very high.

Common symptoms include:

feeling very thirsty
peeing a lot
feeling weak or tired
blurred vision
losing weight

Causes of high blood sugar

Common causes of high blood sugar in people with diabetes include:

being unwell
feeling stressed
eating too much sugary or starchy food
being less active than usual
missing doses of diabetes medicine

You can also get high blood sugar if your diabetes medicine is not working well, you're taking certain medicines (such as steroids) or you recently had an operation.

How to lower your blood sugar

If you have diabetes, it's important to try to stop your blood sugar level getting too high.

Do

take any diabetes medicine you've been prescribed, as advised by your doctor or care team
avoid eating too much sugary or starchy food
try to find ways to manage stress
exercise regularly
lose weight if you're overweight
follow advice from your doctor or care team about what to do while you're ill (sometimes called "sick day rules")

Don’t

do not skip or change doses of your diabetes medicine unless advised by your doctor or care team

Non-urgent advice: Speak to your care team or GP surgery if:

you've tried to lower your blood sugar but your blood sugar level is still high or you still have symptoms
you have symptoms of high blood sugar and you have not been diagnosed with diabetes

Problems caused by high blood sugar

It's not usually a serious problem if your blood sugar is sometimes slightly high for a short time.

But high blood sugar can cause serious problems if it stays high for a long time or gets to a very high level.

It can lead to:

permanent damage to the nerves in your hands and feet (peripheral neuropathy)
permanent damage to your eyes and problems with your sight (diabetic retinopathy)
life-threatening conditions such as diabetic ketoacidosis

If you have high blood sugar, your doctor or care team may ask you to test your blood or pee to check for ketones. A high level of ketones is a sign of diabetic ketoacidosis.

High blood sugar, also called hyperglycemia, affects people who have diabetes. Several factors can play a role in hyperglycemia in people with diabetes. They include food and physical activity, illness, and medications not related to diabetes. Skipping doses or not taking enough insulin or other medication to lower blood sugar also can lead to hyperglycemia.

It's important to treat hyperglycemia. If it's not treated, hyperglycemia can become severe and cause serious health problems that require emergency care, including a diabetic coma. Hyperglycemia that lasts, even if it's not severe, can lead to health problems that affect the eyes, kidneys, nerves and heart.

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Symptoms

Hyperglycemia usually doesn't cause symptoms until blood sugar (glucose) levels are high — above 180 to 200 milligrams per deciliter (mg/dL), or 10 to 11.1 millimoles per liter (mmol/L).

Symptoms of hyperglycemia develop slowly over several days or weeks. The longer blood sugar levels stay high, the more serious symptoms may become. But some people who've had type 2 diabetes for a long time may not show any symptoms despite high blood sugar levels.

Early signs and symptoms

Recognizing early symptoms of hyperglycemia can help identify and treat it right away. Watch for:

Frequent urination
Increased thirst
Blurred vision
Feeling weak or unusually tired

Later signs and symptoms

If hyperglycemia isn't treated, it can cause toxic acids, called ketones, to build up in the blood and urine. This condition is called ketoacidosis. Symptoms include:

Fruity-smelling breath
Dry mouth
Abdominal pain
Nausea and vomiting
Shortness of breath
Confusion
Loss of consciousness

When to see a doctor

Seek immediate help from your care provider or call 911 if:

You have ongoing diarrhea or vomiting, and you can't keep any food or fluids down
Your blood glucose levels stay above 240 mg/dL (13.3 mmol/L) and you have symptoms of ketones in your urine

Make an appointment with your health care provider if:

You have ongoing diarrhea or vomiting, but you're able to take some foods or drinks
You have a fever that lasts more than 24 hours
Your blood sugar levels stay above 240 mg/dL (13.3 mmol/L) despite treatment, and you have symptoms of ketoacidosis
You have trouble keeping your blood glucose within your target range

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