12 Symptoms of High Blood Sugar (Hyperglycemia)

How do you feel when your blood sugar is too high? The answer can vary depending on the person. Signs can be subtle and include a frequent need to pee, headaches, or feeling thirstier than usual. High blood sugar can also cause life-altering complications such as heart disease and vision loss if not treated.

High blood sugar is a shared experience of people with diabetes. The condition is medically known as hyperglycemia. When you don't produce any or enough insulin, or it is not being used efficiently, glucose remains in the blood. Blood glucose, or blood sugar, can increase and cause high glucose levels. Here's what else you need to know.

What Is High Blood Sugar, or Hyperglycemia?

Hyperglycemia is the term for increased blood sugar. Blood sugar is typically considered high for someone with diabetes when the levels are over the following thresholds:

• Before eating: 80 to 130 milligrams per deciliter (mg/dL)
• Within two hours of starting a meal: Less than 180mg/dL

Keep in mind that your blood sugar targets may be different based on factors like age and other health conditions you may have. The targets are also different for people without diabetes.

How Does It Feel When Your Blood Sugar Is Too High?

Testing your blood sugar levels, such as with a glucometer, is the main way to tell if your blood sugar is too high. However, even before you check your levels, you may experience symptoms of high blood sugar—though the signs may not always be noticeable at first.

1. Excessive Thirst

Feeling like you can't quench your thirst regardless of how much you drink is a common symptom of very high blood sugar, known as polydipsia. When blood sugar is high, that extra glucose is released through urine. Glucose pulls water into the urine, causing the body to lose even more fluids. The thirst you experience is your body trying to compensate for the extra fluid lost in your urine.

Excessive thirst can increase the risk of dehydration. Being dehydrated for a long time can cause nausea, dizziness, headache, and fainting. Extreme dehydration can also raise blood sugars even higher since less urine and glucose are emptied.  

2. Excessive Urination

Excessive urination goes hand-in-hand with excessive thirst. The thirstier you are, the more you drink. The more you drink, the more you urinate—which is called polyuria.

The increase in urination is also due to your body having to rid itself of more liquid from drinks and high glucose levels. Because glucose gets eliminated in the urine when blood sugar is high, there is more liquid for your body to eliminate.

3. Extreme Hunger

Polyphagia is when someone with high blood sugar might have to eat a lot of food before feeling full. As excess glucose is released in urine, the glucose calories are also released. That means you are not taking in the calories, leading to hunger.

4. Fatigue

Extreme fatigue or tiredness occurs because your body is unable to use the glucose from food you eat for energy. Insulin moves the glucose to cells to make that energy. However, a lack of insulin means glucose stays in the blood instead of being moved to cells as an energy source. Since the glucose stays in your blood, it remains unused and can make you feel exhausted and sleepy.

5. Unexplained Weight Loss

Weight loss not due to any other health condition or a lifestyle change can be an early but severe sign of high blood sugar. When glucose can't be used for energy, the body still needs a way to get energy and pulls it from muscle and fat. As muscle and fat start to get burned for energy, your weight may decrease.

6. Blurry Vision

High blood sugar can increase the fluid levels in your eyes, keeping the lenses from changing shape and causing your vision to be blurry. It can also cause swelling in the tissues of your eyes that help you focus, leading to blurriness. This blurred vision is usually temporary and will clear up when your blood sugar levels return to normal.

However, long-term high blood sugar can cause permanent damage to the small blood vessels in the eyes. One condition that this blood vessel damage can lead to is diabetic retinopathy. Diabetic retinopathy can initially make it hard to read or to see objects in the distance. In its later stages, symptoms may include floating spots in your vision, vision loss, and even blindness.

7. Hand or Feet Numbness and Tingling

Numbness and tingling in the hands and feet can occur when a person has poor circulation due to an accumulation of glucose. This symptom is more common in people who have had diabetes for a long time, affecting about half of people with diabetes.

In addition, chronically elevated blood sugars can damage the nerves. This condition is known as diabetic neuropathy. There are different types of diabetic neuropathy, each of which can affect different parts of the body. The most common type is peripheral neuropathy, which affects the feet, legs, and sometimes the hands and arms.

8. Frequent Infections

High blood sugars may contribute to frequent infections due to a disruption in the body's immune response. Researchers also believe certain bacteria grow better in a high-sugar environment. 

High blood sugar may contribute to an increased risk of bacterial and yeast infections. Infections of the respiratory and urinary tracts are especially common for people with diabetes.

9. Skin Problems

Hyperglycemia can cause a number of skin changes, including:

• Dry or itchy skin
• Frequent skin infections
• Wounds that are slow to heal

10. Sexual Dysfunction

Chronically elevated blood sugars can eventually lead to nerve damage in the genitals. For example, high blood sugar can damage the nerves that are needed to maintain an erection. Hyperglycemia is associated with sexual dysfunction in people with female reproductive organs as well. However, more research is needed to understand the link more clearly.

11. Reduced Fertility

Having difficulty conceiving could be a sign of high blood glucose, which can lead to reduced fertility and egg quality. It's important to continue monitoring and managing your blood glucose levels if you're trying to become pregnant and throughout the pregnancy.

Elevated blood sugar levels during the first few weeks of pregnancy can raise the risk of miscarriages or congenital disorders in the fetus later in the pregnancy. Also, some studies have suggested hyperglycemia may negatively impact sperm production, size, movement, and quality. All of these factors are linked to reduced fertility and infertility.

12. Mood Changes

Understanding the direct impact of high blood sugar on mood is difficult to measure accurately. Still, many people with diabetes have reported changes in blood sugar—high or low—can cause changes in mood and behavior.

In a literature review published in 2020, researchers found a significant association between a higher rate of after-meal glucose increase and more negative mood symptoms. However, they suggested that the evidence was unclear and that the relationship needed higher-quality research.

Could You Be at Risk of Diabetes?

Not everyone who has high blood sugar has type 2 diabetes. However, hyperglycemia can raise your risk of developing diabetes. Your healthcare provider is best fit to give you an accurate diagnosis of your condition, but the quiz below can help you assess your risk level and learn when to reach out for medical support.

Prevention of High Blood Sugar

Knowing the reason behind high blood sugar helps you figure out how to prevent it from happening again. Try to understand what changes could have triggered a blood sugar spike, whether by looking at your diet or activity levels.

Other preventative measures include:

• Checking your blood sugar levels regularly
• Exercising regularly—at least 150 minutes per week
• Following your meal plan for diabetes
• Getting routine checkups with healthcare providers on your treatment team
• Taking medications for diabetes correctly

Also, seeing an ophthalmologist or optometrist can help you monitor any eye problems. All people newly diagnosed with type 2 diabetes should receive a dilated eye exam shortly after diagnosis and every year after that. It’s also recommended that people with type 1 diabetes receive a dilated eye exam within five years of a diagnosis and every year after that.

When To See a Healthcare Provider

Consult a healthcare provider for a change in your treatment plan if you have been experiencing high blood sugar regularly. This doesn't mean you haven't been managing your diabetes well. Diabetes is a progressive disease that can change how it affects you over time. Making changes to medications, meal plans, and exercise regimens might be necessary to help you achieve better control over your blood sugar levels.

When To Seek Emergency Medical Treatment

In some cases, high blood sugar can be an emergency. Get medical attention immediately if you experience symptoms of diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar state (HHS).

Diabetic Ketoacidosis

You can develop the life-threatening complication of DKA if high levels of blood sugar aren’t treated. The condition—which is more common in type 1 diabetes—can cause a build-up of ketone, a type of acid, in your blood.

Sometimes, DKA can be the first sign of diabetes for those who have not yet been diagnosed. Left untreated, DKA can result in coma or death. DKA can develop slowly at first, with its initial symptoms including thirst, a very dry mouth, and frequent urination. The condition can worsen quickly, with later symptoms including:

• Deep, shallow breathing
• Fruity breath
• Headache
  
• Muscle aches and stiffness
• Stomachache
• Vomiting

Hyperglycemic Hyperosmolar State

High blood sugar levels mixed with dehydration can also lead to hyperglycemic hyperosmolar state (HHS). HHS is more common among people with type 2 diabetes who have had an infection of some kind, such as pneumonia or a urinary tract infection.

HHS can present as extremely high blood sugars (600mg/dL) with fever, confusion, or weakness or paralysis on one side of the body. Immediate treatment is necessary to prevent serious consequences.

A Quick Review

You can experience classic high blood sugar symptoms such as increased urination or increased thirst or hunger, while weight loss and blurry vision may seem less obvious. A treatment plan change may be necessary to get your blood sugars back in a healthy range if you have diabetes and experience high blood sugar signs.

If you do not have diabetes but are experiencing symptoms of hyperglycemia, reach out to a healthcare provider for screening. Early detection and treatment can help to delay and manage diabetes and diabetes-related complications.