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- Hyperglycemia is when blood sugar levels are 130 mg/dL before a meal, or 180 mg/dL two hours after a meal.
- Signs and symptoms of hyperglycemia include increased thirst, urinating more frequently, and blurry vision.
- Hyperglycemia mostly occurs for people with diabetes, though it can also happen as a result of stress or steroid medication.
- This article was reviewed by Jason R. McKnight, MD, MS, a family-medicine physician and clinical assistant professor at Texas A&M College of Medicine.
- Visit Insider’s Health Reference library for more advice.
Hyperglycemia is when you have elevated blood sugar. Before a meal, or when you have not eaten in several hours, high blood sugar is defined as 130 mg/dL. Two hours after eating, hyperglycemia is when blood sugar levels are above 180 mg/dL.
By comparison, normal blood sugar levels are generally between 80 mg/dL and 130 mg/dL. Hyperglycemia is most common for people with diabetes, and essentially, it describes the high blood sugars that define the chronic condition.
In some cases, hyperglycemia can also occur as a result of stress or as a side effect of steroid medication. Here’s how you can recognize the signs of high blood sugar and lower it quickly.
Signs and symptoms
The most common symptoms of hyperglycemia include:
- Increased thirst
- Drinking liquids more frequently
- Urinating more frequently
- Blurry vision
- Weight loss
However, the only way to know for sure if you have hyperglycemia is with a blood draw, says Jordan Messler, MD, a hospitalist at Morton Plant Hospitalist group in Clearwater, Florida. This can confirm that your blood sugar levels are elevated, and by how much. In fact, symptoms often won’t become severe until blood sugars rise above 200 mg/dL.
If left untreated, hyperglycemia can lead to diabetic ketoacidosis (DKA) within 24 hours in some cases. This condition, most common in people with type 1 diabetes, occurs when the body is not able to break down sugar properly for fuel, so it breaks down fats instead, Messler says. This naturally releases acids into the blood, and because the body cannot flush the acid quickly enough, it becomes toxic in the blood.
DKA is a medical emergency, and people with the following symptoms should visit the emergency room, especially if they have diabetes, Messler says:
- Nausea
- Fatigue
- Shortness of breath
- Dry mouth
- Abdominal pain
Causes
Both type 1 and type 2 diabetes can cause hyperglycemia. But there are also other potential causes, like stress or steroid medications.
Diabetes
People with diabetes are not able to process blood sugar effectively, either because they do not produce insulin, the hormone that breaks down blood sugar (type 1), or because their body does not utilize insulin effectively (type 2).
Since the body cannot break down blood sugar, it builds in the bloodstream and is more likely to cause high blood glucose levels, or hyperglycemia.
Hyperglycemia can also occur occasionally in people who are being treated for diabetes. These spikes in blood sugar levels can be caused by:
- Eating too much
- Not exercising enough
- Giving yourself too little insulin or medication
- The dawn phenomenon, or a surge in hormones during the early morning that can spike blood sugar
- Stress or illness
Stress
Even people without diabetes can get hyperglycemia. For example, stress can cause insulin resistance — a condition where your body doesn't utilize insulin effectively.
At the same time, the stress hormone cortisol encourages the release of hepatic glucose, or glucose stored in the liver, which further raises blood sugar. This so-called "stress hyperglycemia" can occur during acute medical situations, such as an infection or heart attack, Messler says.
Steroids
Steroids, like Prednisone and methylprednisolone, can also cause hyperglycemia in up to 46% of patients without diabetes, but this usually resolves when the medication is stopped.
Like the effect of stress, these medications also increase hepatic glucose release and increase insulin resistance, and can cause hyperglycemia even if you don't have diabetes.
Treatment
The goal of treatment for hyperglycemia is to lower blood sugar. For people with diabetes, this could mean adjusting your insulin dose, or following a plan that you and your doctor have created ahead of time for when you experience hyperglycemia.
People who have chronic hyperglycemia caused by diabetes should also work to lower their blood sugar over time, in addition to treating individual episodes of hyperglycemia.
"The best ways to begin lowering blood glucose, for someone who has diabetes, is through lifestyle changes, such as diet and exercise," Messler says.
People with type 1 diabetes will need insulin to lower blood sugar levels, while type 2 diabetics are often treated with oral medication like metformin, and possibly insulin as well, Messler says.
However, for people with stress or steroid-induced hyperglycemia, the condition usually resolves on its own, as soon as the stress dissipates, or about four to six hours after the medication is discontinued.
If hyperglycemia persists after the underlying health condition is addressed, the patient may be diagnosed with diabetes, Messler says.
Takeaways
Hyperglycemia is a serious condition, especially if left untreated. Since it can only be diagnosed by measuring blood sugar, it's important to talk to your doctor if you're concerned about hyperglycemia.
"If you are suffering from symptoms of increased thirst and frequent urination with weight loss, then you should discuss with your doctor and check your blood sugar," Messler says.
He also recommends that people who have risk factors for diabetes — including being overweight, having a family history of diabetes, or being older than 45 — have their blood sugar levels checked regularly.