Hyperglycaemia – high blood glucose

When your blood glucose levels are too high, it can cause hyperglycaemia (hyper).

This can happen if you're:

  • stressed
  • unwell
  • less active
  • sick
  • not having enough insulin for the carbohydrate you've eaten

Signs of hyperglycaemia

Speak to your care team if your blood glucose levels are high and you:

  • feel very thirsty
  • pee more than normal
  • feel tired all the time
  • lose weight without trying
  • have blurred vision
  • have fruity-smelling breath

Very high blood sugar levels may cause a serious problem called diabetic ketoacidosis (DKA).

Your body starts to break down fat for energy when there's not enough insulin.

This leads to a build-up of acid (ketones) in your blood. It can be life threatening and should be treated in hospital.

Check for ketones if your blood glucose level is higher than 14mmol/L. Your care team will give you a meter that can test for ketones and a prescription for ketone strips.

DKA can develop quickly, over a few hours. Not taking your insulin, infections and drinking too much alcohol are common triggers for DKA.

When to get medical help

Urgent advice: Speak to your care team, GP or emergency department (ED) immediately if

your glucose level is high and you:

  • feel sick or vomiting
  • have ketones in your blood or pee
  • have tummy pain
  • are breathing rapidly
  • are dehydrated
  • are struggling to stay awake

You probably need treatment in hospital. Do not delay in seeking medical attention.

If your blood ketone level is above 0.6mmol/L, follow the advice from your diabetes team. You might need more insulin.

Blood glucose levels and targets - diabetes.ie

Emergency action required: Go to your nearest emergency department (ED) if:

  • your ketone level is above 3.0mmols

This is a medical emergency.


If you need to call an ambulance Dial 112 or 999 and ask the operator to put you through to the ambulance service.

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 9.