What should you know about high glucose in a blood test?

Glucose changes with food, fasting, stress, infection, sleep, activity and some medicines. The meaning depends on whether the sample was fasting, the result's measurement and your symptoms. A clinician may repeat the test or arrange a longer-term glucose test to see whether the finding persists. A raised result can be associated with diabetes, but it can also occur temporarily during illness or treatment. Kidney disease and some inflammatory or infectious illnesses may affect the wider clinical picture, so the result should be interpreted with your history rather than in isolation. Anaemia and other blood conditions can also affect how some longer-term tests are interpreted.

Ask whether you needed to fast and whether any medicines or recent illness could have influenced the sample. Do not stop prescribed treatment without advice. Arrange follow-up to review repeat testing, blood pressure, weight, symptoms and family history. Until you have guidance, choose regular meals, drink water and stay active within your usual ability. If you are being assessed for a condition such as coeliac disease or Crohn's disease, tell the clinician about the glucose result so findings are considered together.

Contact a clinician promptly for marked thirst, passing urine much more often, unexplained weight loss, persistent vomiting, unusual drowsiness or worsening weakness. Seek emergency help for confusion, difficulty breathing, collapse or inability to keep fluids down, especially when these symptoms occur together. A mildly raised result without symptoms still deserves planned follow-up.

Was this sample fasting? Should glucose be repeated or checked with another test? Could illness or a medicine explain the result? What symptoms should prompt urgent review?