Symptoms of Hyperglycemia

Hyperglycemia (high blood sugar) tends to develop gradually in people with type 2 diabetes. In the early stages, symptoms may be so mild that you don't notice them. Some people do not even recognize their hyperglycemia symptoms until years have passed.

If you have already been diagnosed with diabetes, the occasional rise in your blood sugar (glucose) doesn't necessarily put you in immediate danger. But if high blood sugar becomes a chronic problem, it can harm your blood vessels, leading to problems with your eyes, heart, kidneys, and feet.

This article covers the symptoms of high blood sugar. It discusses the complications that can come from uncontrolled hyperglycemia, along with when to see a healthcare provider.

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Frequent Symptoms

In the beginning stages of hyperglycemia, symptoms can be so mild that people with undiagnosed diabetes may not recognize them as telltale diabetes warning signs.

If you have been diagnosed with diabetes and are experiencing the following symptoms, you should inform your healthcare provider. This could mean that your treatment plan needs adjusting.

Excessive Thirst (Polydipsia)

It's largely up to your kidneys to regulate your blood sugar. Under normal circumstances, your kidneys filter excess glucose from your blood and reabsorb it so that your urine has little to no glucose.

If you are hyperglycemic, this process becomes much more difficult on your kidneys because they need to work overtime to absorb the excess glucose. They pull fluids from your tissues to dilute the sugar and excrete more glucose into your urine to keep your blood sugar balanced.

The more fluids your tissues lose, the stronger your urge to drink. If you find that no matter how much you drink, you still feel parched or that your mouth is severely dry, this may be a sign of hyperglycemia.

Increased Urination (Polyuria)

More frequent trips to the bathroom, especially at night, can be a sign of high blood sugar. This results from the kidneys drawing extra water out of your tissues to dilute the extra sugar in your blood and get rid of it through the urine.

Increased Hunger (Polyphagia)

Excess sugar in your bloodstream means your body cannot use it for fuel. Hence, your cells become starved for energy, causing you to feel extra hungry. But the more carbohydrates you consume, the higher your blood sugars rise.

Blurry Vision

High sugar levels force the body to pull fluid from your tissues, including the lenses of your eyes. This can affect your ability to focus and result in blurry vision.


Normally, your cells absorb blood sugar for energy. But when sugar stays in the blood instead of being taken to your cells, your cells become starved of food. In turn, you end up feeling sluggish or fatigued. This can commonly happen after you've eaten a meal, particularly one rich in carbohydrates.

Yeast Infections

Since yeast feeds on sugar, having elevated blood sugar levels can result in an overgrowth of yeast. For women with hyperglycemia, this can lead to frequent yeast infections.

Severe Symptoms

These particular symptoms tend to occur when someone has had hyperglycemia for a long time, or when the blood sugar is extremely elevated. They usually indicate an emergency.

Stomach Pain

Chronic hyperglycemia can result in nerve damage to the stomach gastroparesis, also known as delayed gastric emptying. Gastroparesis can cause nausea and extra slow digestio.

Stomach pain can also be a sign of diabetic ketoacidosis, a medical emergency that needs to be treated right away.

Weight Loss

Unintentional weight loss is an important sign of elevated blood sugars, particularly in kids drinking and urinating often. Many children diagnosed with type 1 diabetes lose weight before diagnosis. This usually occurs because the body cannot use the sugar in the bloodstream for fuel.

Mouth and Breathing Changes

Nausea, vomiting, fruity breath, deep and rapid breathing, and loss of consciousness are indications that you need to seek emergency help. These symptoms can be warning signs of other diabetes-related conditions that can result in death if not treated immediately.

Rare Symptoms

Some more rare symptoms can occur in people with hyperglycemia, too. 


Nerve damage in the extremities, known as peripheral neuropathy, occurs over time and can present as numbness, tingling, or pain in the hands, feet, or legs.

Skin Conditions

Dry, itchy skin, and wounds or cuts that are slow to heal can be an indication of hyperglycemia. Another sign that points to insulin resistance is acanthosis nigricans, a condition in which thick, velvety patches form in the folds or creases of areas like the neck.

Erectile Dysfunction

Men with diabetes are three times more likely to develop erectile dysfunction than men who don't have diabetes. Much of this is due to how hyperglycemia damages the blood vessels needed to get or maintain an erection.

Hyperglycemic Hyperosmolar Nonketotic Syndrome

Hyperglycemic hyperosmolar nonketotic coma (HHNKC) is an extremely serious complication which can happen in those with type 1 or type 2 diabetes. It most often occurs in those who are non-insulin dependent (type 2 diabetes).

HHNKC is characterized by dangerously high blood sugar over 600 mg/dL. It is typically brought on by an infection such as pneumonia, a urinary tract infection, or uncontrolled blood sugar. If left untreated, it can result in coma and even death.

Signs and symptoms include:

  • Extreme thirst
  • Confusion
  • Fever (usually over 101 degrees)
  • Weakness or paralysis on one side of the body

The best way to prevent HHNKC is to take your medications as directed and to keep in contact with your healthcare team when your blood sugar is consistently over 300 mg/dL.

Diabetic Ketoacidosis

Hyperglycemia can lead to another dangerous condition called diabetic ketoacidosis (DKA). This condition most commonly occurs in people who have type 1 diabetes.

DKA happens when the body has little or no insulin to use. As a result, blood sugars rise to dangerous levels, and the blood becomes acidic. From this, cell damage can occur. If it continues to progress, it can cause coma or death.

DKA needs immediate medical intervention. People with DKA will need to be monitored by a medical professional and given intravenous fluids, electrolytes, and insulin.

Like hyperglycemia, DKA tends to develop slowly. The first symptoms are usually intense thirst and excessive urination. If left untreated, more severe symptoms can come on quickly and may include:

  • Fast, deep breathing
  • Dry skin and mouth
  • Flushed face
  • Fruity-smelling breath
  • Headache
  • Muscle aches and stiffness
  • Being very tired
  • Nausea and vomiting
  • Stomach pain


Chronic hyperglycemia can lead to a host of complications known as micro (small) and macro (large) vascular issues. They include damage to the:

Additionally, chronically elevated blood sugars can cause or worsen heart disease and peripheral arterial disease, in which narrowed arteries reduce blood flow to the arms and legs.

During Pregnancy

Hyperglycemia in pregnancy can be particularly damaging to an expectant mother and unborn child.

According to the ADA, uncontrolled diabetes in pregnancy can pose risks such as:

  • Spontaneous abortion (loss of pregnancy before 20 weeks)
  • Fetal anomalies (problems with the baby's development during pregnancy)
  • Preeclampsia (uncontrolled blood pressure in mother)
  • Fetal demise (delivery of a deceased fetus)
  • Macrosomia (large baby)
  • Hypoglycemia (low blood sugar) in babies at birth
  • Neonatal jaundice (liver condition that causes yellowing of the newborn's skin and eyes)

In addition, diabetes in pregnancy may increase the risk of obesity and type 2 diabetes in offspring later in life.

ADA guidelines for women with diabetes emphasize the importance of preconception counseling. It should address the importance of achieving glucose levels as close to normal as is safely possible—ideally A1C <6.5% (48 mmol/mol). This is vital to reduce the risk of serious complications in both the mother and baby.

In Children

Hyperglycemia in children, especially when undiagnosed, can lead to the development of type 2 diabetes or ketoacidosis in those children who have type 1 diabetes.

Children with diabetes who have chronically elevated glucose levels are at increased risk for developing diabetes complications.

When to See a Healthcare Provider

If you don't feel like your usual self and have any symptoms of high blood sugar, test it to confirm.

If your blood sugar happens to be elevated and it's an isolated event, odds are that you can probably get it back to normal on your own. Go for a walk or do some light exercise, drink extra water, and take your medicine as prescribed.

On the other hand, if you are experiencing elevated blood sugars for several consecutive days, give your medical team a call, as you may need to tweak your treatment plan. 

If you don't have diabetes and notice any of these signs or symptoms, are overweight or obese, or have a family history of diabetes, you should schedule an appointment with your healthcare provider to be screened. Both macro and microvascular complications of diabetes can occur before diagnosis, so the sooner you receive treatment, the better.

If you've noticed that your child is drinking, eating, and urinating more often than usual, a trip to the healthcare provider is a good idea, especially if you've seen a quick change in their weight. If the symptoms appear to be more severe and resemble those of DKA, go to the emergency room right away.

If your child has symptoms of hyperglycemia and their blood sugar is greater than 240 mg/dL, they should be tested for ketones. In the event of a positive test, depending on the severity of the ketones, you may be advised to go to the emergency room.


Hyperglycemia (high blood sugar) is an early warning sign of diabetes. It causes symptoms that are characteristic of diabetes, such as excessive thirst and hunger, increased urination, and fatigue.

Hyperglycemia symptoms tend to begin gradually and may go unnoticed until more serious complications occur. Left untreated, excess blood sugar can damage blood vessels and nerves and may eventually harm the eyes, heart, kidneys, and feet.

A Word From Verywell

If you have never been diagnosed with hyperglycemia or diabetes, early signs of elevated blood sugar can be tricky to recognize. Excessive thirst, hunger, and urination can all occur due to short-term or unrelated conditions. But if you find that these issues won't go away no matter how much you eat, drink, or use the restroom, you could be dealing with hyperglycemia. Generally, if you are experiencing new or unusual symptoms of any kind, it's best to reach out to your healthcare provider for an evaluation.

Frequently Asked Questions

  • Are the symptoms of nondiabetic hyperglycemia and diabetic hyperglycemia the same?

    They are very similar. Both diabetic and nondiabetic hyperglycemia may cause:

    • Excessive thirst or hunger
    • Frequent urination
    • Blurry vision
    • Nausea and vomiting
    • Fatigue
  • What are the signs that you’ve developed ketoacidosis?

    In the early stages, ketoacidosis symptoms are just like hyperglycemia symptoms: Excessive thirst, frequent urination, and high blood glucose. As it progresses, you may have extreme hunger with unexpected weight loss, feel fatigued and confused, experience trouble breathing, and have dry skin.

  • Does being constantly hungry mean I have diabetes?

    Maybe. You should have your blood sugar checked if you have other symptoms, especially increased thirst and an increased need to urinate. However, other conditions can cause intense hunger, known as polyphagia, including thyroid diseases, infection, and hormonal fluctuations.

15 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.
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By Barbie Cervoni MS, RD, CDCES, CDN
Barbie Cervoni MS, RD, CDCES, CDN, is a New York-based registered dietitian and certified diabetes care and education specialist.