SymptomsBy Mayo Clinic staff
Hyperglycemia doesn't cause symptoms until glucose values are significantly elevated — above 200 milligrams per deciliter (mg/dL), or 11 millimoles per liter (mmol/L). Symptoms of hyperglycemia develop slowly over several days or weeks. The longer blood sugar levels stay high, the more serious the symptoms become.
Early signs and symptoms
Recognizing early symptoms of hyperglycemia can help you treat the condition promptly. Watch for:
- Frequent urination
- Increased thirst
- Blurred vision
Later signs and symptoms
If hyperglycemia goes untreated, it can cause toxic acids (ketones) to build up in your blood and urine (ketoacidosis). Signs and symptoms include:
- Fruity-smelling breath
- Nausea and vomiting
- Shortness of breath
- Dry mouth
- Abdominal pain
When to see a doctor
Call 911 or emergency medical assistance if:
- You're sick and can't keep any food or fluids down, and
- Your blood glucose levels are persistently above 240 mg/dL (13 mmol/L) with ketones in your urine
Make an appointment with your doctor if:
- You experience ongoing diarrhea or vomiting, but you're able to take some foods or drinks
- You have a fever that lasts more than 24 hours
- Your blood glucose is more than 240 mg/dL (13 mmol/L) even though you've taken your diabetes medication
- You have trouble keeping your blood glucose within the desired range
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