Go to page content

Symptoms of high blood sugar

The symptoms of high blood sugar vary from one person to the next. Normal symptoms include tiredness, an increased need to urinate and dry mouth.

A blood sugar level of 10 mmol/l can cause clear symptoms in someone and no symptoms in someone else. In addition to the current blood sugar level, the symptoms are affected by the long-term blood sugar level, the rate of increase in the blood sugar level as well as the underlying causes, especially if the cause is insulin deficiency.

If the blood sugar balance has been high for a long time, for example, the blood sugar level is mostly around 10–15 mmol/l, the body gets used to it, and the symptoms of high blood sugar are milder.

If the blood sugar level is good or quite low, for example, mostly around 4–7 mmol/l, the body can get used to it, too, and the symptoms of high blood sugar can occur already when the blood sugar level rises above 7–8 mmol/l.

A common symptom of high blood sugar is tiredness and "sluggishness" of thought processes. If the blood sugar level exceeds 10 mmol/l, the extra sugar is secreted into urine, resulting in increased urine excretion. This dries up the mucous membranes and makes you feel thirsty. In a child or an elderly person, for instance, the increased excretion of urine can result in wetting yourself.

High blood sugar causes some people to experience variations in their eyesight and numbness in the soles of their feet.

In elderly people, high blood sugar can lead to impaired general condition and ability to function or confusion.

If the increase in blood sugar is due to lack of insulin, the body will accumulate ketone, which can cause nausea and vomiting. In an advanced stage, insulin deficiency leads to diabetic ketoacidosis (DKA).

Updated 30.9.2023