Hyperglycemia in Diabetes

Hyperglycemia happens when there’s too much sugar (glucose) in your blood. It’s also called high blood sugar or high blood glucose. This happens when your body has too little insulin (a hormone) or if your body can’t use insulin properly (insulin resistance).

Hyperglycemia usually means you have diabetes, and people with diabetes can experience hyperglycemia episodes frequently.

If you have hyperglycemia that’s untreated for long periods of time, it can damage your nerves, blood vessels, tissues and organs.

Severe hyperglycemia can also lead to an acute (sudden and severe) life-threatening complication called diabetes-related ketoacidosis (DKA), especially in people with diabetes who take insulin or people with undiagnosed Type 1 diabetes. This requires immediate medical treatment.

What blood sugar level is hyperglycemia?

For people undiagnosed with diabetes, hyperglycemia is blood glucose greater than 125 mg/dL (milligrams per deciliter) while fasting (not eating for at least eight hours).

A person has prediabetes if their fasting blood glucose is 100 mg/dL to 125 mg/dL.

A person with a fasting blood glucose greater than 125 mg/dL on more than one occasion usually receives a diabetes diagnosis — typically Type 2 diabetes. People with Type 1 diabetes usually have very high blood sugar (above 250 mg/dL) upon diagnosis.

For a person with diabetes, hyperglycemia is usually considered to be a blood glucose level greater than 180 mg/dL one to two hours after eating. But this can vary depending on what your target blood sugar goals are.

What is blood sugar?

Glucose (sugar) mainly comes from carbohydrates in the food and drinks you consume. It’s your body’s main source of energy. Your blood carries glucose to all of your body’s cells to use for energy.

If you don’t have diabetes, several bodily processes naturally help keep your blood glucose in a healthy range. Insulin, a hormone your pancreas makes, is the most significant contributor to maintaining healthy blood sugar.

High blood sugar most often happens due to a lack of insulin or insulin resistance. This leads to diabetes. People who have diabetes must use medication, like oral diabetes medications or synthetic insulin, and/or lifestyle changes to help keep their blood sugar levels in range.

How common is hyperglycemia?

Hyperglycemia and diabetes are very common — about 1 in 10 people in the United States has diabetes. Hyperglycemia episodes are also very common in people with diabetes.