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. However, some people who've had type 2 diabetes for a long time may not show any symptoms despite elevated blood sugars.

Early signs and symptoms

Recognizing early symptoms of hyperglycemia can help you treat the condition promptly. Watch for:

  • Frequent urination
  • Increased thirst
  • Blurred vision
  • Fatigue
  • Headache

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
  • Weakness
  • Confusion
  • Coma
  • 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) and you have 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
April 18, 2015