Hyperglycaemia - Causes of hyperglycaemia

Hyperglycaemia (a high blood glucose level) usually only happens in people with diabetes.

The food that you eat is digested and broken down into other substances, including a simple sugar called glucose that then enters your bloodstream.

The amount of glucose in your blood is controlled by a hormone called insulin, which is produced by your pancreas (an organ lying behind the stomach). Insulin takes glucose out of your blood and moves it into your cells, where it is broken down to produce energy.

Diabetes

In people with diabetes, the body is unable to break glucose down into energy. This is because there is either not enough insulin to move the glucose, or because the insulin that is there does not work properly. The glucose remains in the blood, causing a high blood glucose level.

The high blood glucose level means that glucose enters the urine. The glucose takes extra water and electrolytes (minerals and salts in the blood) with it into the urine.

This causes the symptoms of hyperglycaemia, such as increased thirst and the need to urinate frequently. Eventually, this can lead to dehydration.

Hyperglycaemia triggers

There are some events that can trigger an increase in blood glucose if you have diabetes, including:

stress
changing your diet, or eating too much
a wrong (or missed dose) of insulin
over-treating an episode of hypoglycaemia (low blood sugar)
an illness, such as a cold
a change of medication (see below)

If you have diabetes, your GP will give you advice about how to manage your blood glucose levels.

Medications and hyperglycaemia

Some medications can cause hyperglycaemia as a side effect in people with diabetes. Examples of these medications include olanzapine and risperidone (used to treat mental health conditions), and steroid medication (used to relieve inflammation)

If you are prescribed a medication that could cause hyperglycaemia, your GP may arrange for your weight and blood glucose levels to be monitored during treatment in case your blood glucose level starts to increase.

Pregnant women

Some pregnant women experience hyperglycaemia as a result of gestational diabetes. This is a type of diabetes that can develop if your body is unable to produce enough extra insulin to meet the demands of pregnancy, leading to an increased level of glucose in the blood.

Most cases of gestational diabetes disappear after the baby is born.

Children

Children with hyperglycaemia may have undiagnosed diabetes. This will usually be type 1 diabetes but it could be type 2 diabetes if the child is obese (although this is rare).

Newborn babies

Some babies develop hyperglycaemia soon after being born. This is particularly common in babies born prematurely (before 37 weeks of pregnancy) and with a very low birthweight.

Some cases occur as a result of an underlying problem, such as blood poisoning (sepsis) or a condition called neonatal respiratory distress syndrome (NRDS), but very few cases are caused by diabetes.

Babies with hyperglycaemia often get better without treatment and without any lasting problems, although a few cases are serious and can be life-threatening.

Heart conditions

Hyperglycaemia can also occur in people who have experienced a condition called acute coronary syndrome (ACS).

This is a group of heart problems that includes heart attacks and unstable angina.