Hyperglycemia, or high blood sugar, is a common issue in people with diabetes. Spikes in blood sugar can lead to immediate complications, while chronic high blood sugar can cause long-term complications.

Hyperglycemia happens when your blood sugar levels are too high. You may also hear it called high blood glucose or high blood sugar.

The exact blood sugar levels for what’s considered hyperglycemia can vary. One definition is that hyperglycemia is when your blood sugar is over 125 mg/dL while fasting or over 180 mg/dL after a meal.

While hyperglycemia is a common issue for people with diabetes, it can occur in other situations. Having hyperglycemia can lead to both immediate and long-term complications.

When blood sugar levels are elevated, it leads to symptoms like fatigue, thirst, and frequent urination. As levels continue to increase, you can experience more serious symptoms like vision problems and confusion.

If blood sugar levels become very high, it can lead to two potentially life threatening complications: diabetic ketoacidosis and hyperosmolar hyperglycemic state. These can lead to coma and death.

Diabetic ketoacidosis

Insulin is a hormone made by the pancreas. Typically, your pancreas releases insulin after you eat to move glucose into your cells to be used as an energy source.

However, in diabetes, the body either doesn’t make insulin or doesn’t use insulin effectively. Diabetic ketoacidosis (DKA) happens when your body doesn’t have enough insulin to effectively move glucose into cells.

When this occurs, blood sugar levels remain high, and your body instead breaks down fat from your liver for energy. The process of breaking down this fat makes acids called ketones. Ketones can build up in the blood and make it more acidic.

DKA is more common in people with type 1 diabetes. It can develop slowly, but if left untreated, severe symptoms can come on in a matter of hours.

DKA can cause symptoms like:

Hyperosmolar hyperglycemic state

Hyperosmolar hyperglycemic state (HHS) is another potential complication of diabetes. It’s similar to DKA but doesn’t involve the production of ketones or increases in blood acidity. Usually, someone has an illness or infection prior to HHS.

HHS is characterized by hyperglycemia and severe dehydration. This leads to the blood becoming more concentrated, called high osmolarity.

When blood becomes more concentrated, water is drawn out of other organs and tissues. This can have a profound impact on the brain in particular.

HHS is more common in people with type 2 diabetes and typically comes on more slowly than DKA over a period of days or weeks. Symptoms can include:

Severe hyperglycemia is an emergency

Severe hyperglycemia, including DKA and HHS, is a medical emergency that can lead to coma and potentially death if left untreated.

Because of this, seek immediate medical care if you or another person is experiencing signs or symptoms of very high blood sugar.

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While severe spikes in blood sugar can lead to immediate and life threatening complications, chronic hyperglycemia can cause other health problems over the long term.

Chronic hyperglycemia is generally associated with inadequately managed diabetes. It can damage various organs and tissues throughout your body.

The potential long-term complications of hyperglycemia include:

Researchers have also observed an association between hyperglycemia and an increased risk of dementia. Some research suggests that even mild hyperglycemia can increase this risk.

If you have diabetes, managing blood sugar levels can lower your risk of long-term complications due to hyperglycemia. However, every person is different. Some people may still develop long-term complications despite adequate management.

If you have diabetes, there are strategies to help you keep your blood sugar within a healthy range:

  • Follow your diabetes meal plan, which will typically focus on fresh fruits and vegetables, whole grains, and healthy protein, dairy, and fat options while limiting:
    • foods high in saturated fats, trans fats, and sodium
    • items that contain added sugars
    • sweets, candy, and baked goods
  • Get regular physical activity.
  • Find effective ways to reduce stress, such as deep breathing, going for a walk, or engaging in a hobby.
  • Take steps to manage your weight if you have obesity or overweight.
  • Quit smoking if you smoke.
  • Monitor your blood sugar regularly.
  • Take all medications as directed by your doctor.
  • See a doctor for regular health check-ins.

If you find that your blood sugar levels are often high when you check them, let your doctor know. It’s possible that your diabetes treatment plan may need to be adjusted to more optimally manage your blood sugar levels.

Can you have hyperglycemia without diabetes?

Yes. A few examples of other potential causes of hyperglycemia include:

  • pancreatic disease
  • some hormone disorders like Cushing syndrome
  • medication side effects, such as those of corticosteroids
  • extreme stress, such as due to surgery, trauma, or a serious illness

Can complications still occur if hyperglycemia is being treated?

Yes. However, the risk of complications is reduced when hyperglycemia is managed.

What are the primary symptoms of hyperglycemia?

The three classic symptoms of hyperglycemia are often called the “3 P’s”. These are:

  • polydipsia (intense thirst)
  • polyuria (frequent urination)
  • polyphagia (increased hunger)

What is a hyperglycemic crisis?

A hyperglycemic crisis is an umbrella term that refers to DKA and HHS, the immediate and life threatening complications of hyperglycemia.

Hyperglycemia can lead to immediate, life threatening complications like DKA and HHS. Over time, unmanaged hyperglycemia can also damage organs and tissues in the body, causing a wide variety of long-term complications.

Taking small steps to manage your blood sugar levels every day can help you reduce your risk of complications due to hyperglycemia. If you find that your blood sugar levels are frequently high, meet with a doctor to discuss strategies to lower them.