Hyperglycemia

Also known as high blood sugar or high blood glucose

Hyperglycemia (high blood sugar) is a condition that occurs when the glucose levels in your blood rise too high. Hyperglycemia is commonly a symptom and complication of diabetes. 

Glucose can build up in the blood when the body doesn't produce enough insulin, a hormone that helps manage blood sugar by getting glucose into cells, or can’t use insulin properly. Blood glucose levels that are higher than 130 milligrams per deciliter (mg/dL) while fasting or higher than 180 mg/dL about two hours after a meal are typically considered hyperglycemia. Any tests higher than 200 mg/dL are also considered hyperglycemia.

Symptoms tend to come on slowly and may include frequent urination and increased thirst.

Frequently Asked Questions

  • How do you treat hyperglycemia?

    A combination of lifestyle factors, such as diet and exercise, and medications and insulin are often part of the treatment plan. Your doctor will take into consideration factors such as age, overall health, severity and frequency of high blood glucose levels, and even cognitive function (since self-management can be complicated) when creating an individualized treatment plan.

  • What causes hyperglycemia?

    Problems with the pancreas and/or insulin production can cause blood sugar levels to rise to unhealthy levels. For people with type 1 diabetes, the pancreas isn't able to produce enough insulin. For those with type 2 diabetes, the body becomes resistant to insulin or doesn't produce enough of it. Causes in those without diabetes can include hormone fluctuations or a rise in stress hormones. 

  • What are the symptoms of hyperglycemia?

    For hyperglycemia to cause symptoms, blood glucose levels must reach significantly high levels. When symptoms do develop, they typically come on slowly over several days or weeks and may include excessive thirst, increased hunger, frequent urination, fatigue, and blurry vision. More severe symptoms can include nausea and vomiting, fruity breath, rapid breathing, or loss of consciousness.

Key Terms

A Look at Hyperglycemia on a Cellular Level

Explore an interactive model below that shows an up-close view inside a human liver cell, and how hyperglycemia can occur when glucose and insulin do not properly bind.

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Page Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Diabetes Association. 6. Glycemic Targets: Standards of Medical Care in Diabetes-2020. Diabetes Care. 2020;43(Suppl 1):S66-S76. doi:10.2337/dc20-S006

  2. American Heart Association. Carbohydrates. Updated April 16, 2018.

  3. Monnier L, Colette C, Dejager S, Owens D. Magnitude of the dawn phenomenon and its impact on the overall glucose exposure in type 2 diabetes: is this of concern? Diabetes Care. 2013;36(12):4057–4062. doi:10.2337/dc12-2127

  4. U.S. Centers for Disease Control and Prevention. Insulin resistance and diabetes. Updated August 12, 2019.