Version 1.0.0, 1 May 2026. 003039-NDSS-W Print Share on Facebook Share on X Key facts High blood glucose levels (or hyperglycaemia) are when your blood glucose level is above your healthy range. There are many causes of high blood glucose levels, like being sick, eating more than usual, missing a medicine or insulin dose, or stress. Symptoms of high blood glucose include needing to urinate a lot, being very thirsty, blurred vision, fatigue, or getting infections often. Treat a high blood glucose level by following your health professional’s advice, such as your sick day action plan. Seek medical attention if you have symptoms of DKA or HHS, are vomiting, or your levels are above 15 mmol/L for more than 8 to 12 hours. Your diabetes management may need changing if you have high levels often, so talk to your doctor or diabetes health professional. Related pages All about insulin Sick days Diabetes health checks Finger prick blood glucose checks Diabetes distress and burnout Find a health service Find a health professional or pharmacy in your area. On this page Causes of high blood glucose levels Symptoms of a high blood glucose level How to treat a high blood glucose level When to get urgent medical help Preventing high blood glucose levels More information and support When you live with diabetes, your blood glucose level may sometimes go too high. This is called hyperglycaemia. Anyone living with diabetes can have high blood glucose levels, and it does not mean you have done anything “wrong”. But if it happens often, it may mean that your diabetes management plan needs changing. Causes of high blood glucose levels There are many reasons your blood glucose levels could go too high, including: being sick or injured not having enough diabetes medicine or insulin eating more carbohydrates than usual being less active than usual feeling stressed or excited hormone changes. Symptoms of a high blood glucose level High blood glucose levels can happen slowly over hours or days. This means you may not notice symptoms until your blood glucose is very high. If you have these symptoms, it is important to act straight away. You may: pass urine (pee) more often feel very thirsty feel tired and weak have a headache have blurry vision have wounds that heal slowly get thrush or other infections often. How to treat a high blood glucose level Your doctor or diabetes educator can give you a diabetes management plan or sick day action plan. This plan will tell you what to do if you have a high blood glucose level. The plan may tell you to: drink lots of water check your blood glucose level often check for ketones change your insulin or medicine doses. If you do not have a plan for treating high blood glucose levels, ask your doctor or diabetes educator to make you one. When to get urgent medical help Call 000 or go to your nearest hospital if: you are sick and can’t keep any food or fluids down your blood glucose levels are above 15 mmol/L for more than 8 to 12 hours you are unable to keep looking after your diabetes or yourself. If your blood glucose level stays high even after following your plan, it may be a sign of a more serious condition. Diabetic ketoacidosis (DKA) DKA mainly happens in people with type 1 diabetes, but can sometimes happen in people with type 2 diabetes if they get very sick. DKA is a medical emergency and must be treated in hospital. It happens when the body does not have enough insulin to use glucose for energy. It must use fat instead. This results in a build-up of ketones in the blood, which makes the blood too acidic. DKA can happen when you are unwell, or if you don’t take enough insulin. Symptoms of DKA Include: feeling drowsy, confused, or weak deep, fast breathing or feeling short of breath tummy pain ongoing vomiting or diarrhoea extreme thirst, dry mouth, and not needing to pass urine (pee) a fruity smell to your breath. Get urgent medical help if you have DKA symptoms. Hyperosmolar hyperglycaemic state (HHS) IHHS is a serious condition that can happen in people with type 2 diabetes. When your blood glucose levels are high, the body tries to get rid of the extra glucose through your urine (pee). This causes you to urinate more often, which can make you dehydrated. High blood glucose levels plus severe dehydration can lead to HHS. Symptoms of HHS may develop over several days and include: very high blood glucose levels (often over 30.0 mmol/L) extreme thirst and/or a dry mouth urinating (peeing) often feeling drowsy, weak, or confused dry skin fever. Get urgent medical help if you have symptoms of HHS. Preventing high blood glucose levels Having a high blood glucose level every now and then is normal when you have diabetes. But if your blood glucose level is above your target range too often, your risk of diabetes-related complications is higher. That is why it’s important to try and keep your blood glucose levels in your target range as much as possible. Ways to help keep your blood glucose levels in range include: Healthy eating Choosing healthy foods and sticking to regular mealtimes can help keep your blood glucose levels stable and avoid highs and lows. Physical activity Physical activity can help lower your blood glucose levels. This is because movement helps the body to use glucose as fuel for your muscles. Taking your diabetes medicine or insulin If you have been prescribed diabetes medicine or insulin, making sure you take it as directed will help keep your blood glucose levels in your target range. Recording your blood glucose levels If you monitor your blood glucose levels, recording your readings in a diary or app will help you and your doctor or diabetes educator to see any patterns in your levels. This will help them see if your treatment needs changing. Seeing your doctor or diabetes educator regularly The way you need to manage your diabetes will change over time, so it is important to see your doctor or diabetes educator regularly. This way they can make sure that your treatment plan is working well and make any changes you may need. When to see a health professional Tell your doctor or diabetes educator if: you feel symptoms of high blood glucose levels often your blood glucose checks show your levels are above your target range often or at certain times of day you are worried about your blood glucose levels you don’t know what to do if your levels are high. If you have symptoms of DKA or HHS, call 000 or go to your nearest hospital straight away. What this means for you High blood glucose levels can happen from time to time, despite your best efforts. But if they happen often, or stay high for a long time, you have a higher risk of diabetes-related complications. Make sure you have a plan for treating high blood glucose from your doctor or diabetes health professional. If your blood glucose levels are often above your target range, let your doctor or diabetes educator know. Your diabetes management may need changing. More information and support Call the NDSS Helpline on 1800 637 700 to ask to speak to a diabetes educator Find a credentialled diabetes educator: Go to the Australian Diabetes Educators Association website to find a credentialled diabetes educator near you. Get peer support: Visit the NDSS Peer Support website to learn about peer support, read about others living with diabetes, or search the directory of online and face-to-face peer support groups across Australia. Dislaimer This information is intended as a guide only. It should not replace individual medical advice and if you have any concerns about your health or further questions, you should contact your health professional. Sources Healthdirect. Hyperglycaemia (high blood sugar) (2024). Royal Australian College of General Practitioners (RACGP). Management of type 2 diabetes: A handbook for general practice. Managing glycaemic emergencies (2024). The Management of Type 1 Diabetes in Adults. A Consensus Report by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) (2021). Australasian Paediatric Endocrine Group (APEG) and Australian Diabetes Society. National evidence-based clinical care guidelines for type 1 diabetes in children, adolescents and adults (2011).
