High blood sugar (hyperglycaemia)

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.

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 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

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.

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

• 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")

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

• 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

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)
• heart disease and stroke
• 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.

A blood sugar test can tell you if your level is high. What counts as a high level depends on the type of test you have and your circumstances.

Symptoms of high blood sugar include feeling very thirsty, peeing a lot and feeling weak or tired.

If you have diabetes, common causes of a high blood sugar level include being ill, feeling stressed and eating too much sugary or starchy food.

Things that can help you lower high blood sugar include taking any diabetes medicine you’re given, cutting down on starchy food and staying active.

High blood sugar can cause problems if not treated, including damage to your nerves or eyes, and a serious condition called diabetic ketoacidosis.