Symptoms of Hyperglycemia

According to the American Diabetes Association (ADA), in patients with type 2 diabetes, hyperglycemia (high blood glucose) typically develops gradually and, at earlier stages, is often not severe enough for you to notice any classic symptoms. This may be why many people are undiagnosed for many years, but being able to recognize the symptoms of high blood sugar can help you to diagnose diabetes, manage it better, and prevent an emergency.

For those people already diagnosed with diabetes, having a blood sugar that is sporadically higher than usual doesn't necessarily put you in immediate danger. However, chronically elevated blood sugar may be problematic. Over time, blood sugar levels that are too high can affect the small and big vessels of the body, leading to complications of the eyes, heart, kidneys, and feet.

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Frequent Symptoms

Experiencing common hyperglycemia symptoms may be a diabetes warning sign for those who have not yet been diagnosed. If you know you have diabetes, noting these symptoms may be an indication that a tweak in your treatment plan is needed.

Excessive Thirst (Polydipsia)

In an effort to restore blood sugar balance, your body tries to get rid of excess sugar through urine. As a result, the kidneys are forced to work overtime absorbing excess sugar. But, because they are unable to keep up with the glucose load, they pull fluids from your tissues along with the excess sugar.

The more fluid you lose, the stronger your urge is to drink. If you find you can continuously drink and not feel as though your thirst is quenched, or that you have a severely dry mouth, this may be a sign of hyperglycemia.

Increased Hunger (Polyphagia)

Excess sugar in your bloodstream means that your body is unable to utilize it for fuel. Hence, your cells become starved for energy and you feel extra hungry and, in extreme cases, insatiable. But the more carbohydrates you consume, the higher your blood sugars rise.

Increased Urination (Polyuria)

More frequent trips to the bathroom, especially at night, can be a sign of high blood sugar. This is a result of 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.

Blurry Vision

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


When sugar remains in the blood as opposed to being taken to the cells for energy, your cells become starved of food, leaving you to feel sluggish or fatigued. This can commonly happen after you've eaten a meal, particularly one that is rich in carbohydrates.

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). 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, particularly in kids who are drinking and urinating often, that the blood sugars are elevated. Many children who are diagnosed with type 1 diabetes lose weight prior to diagnosis. This usually occurs because the body is not able to 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, wounds or cuts that are slow to heal, and acanthosis nigricans (thick, velvety patches found in the folds or creases of areas like the neck, indicative of insulin resistance) can be an indication of hyperglycemia.

Frequent Yeast Infections and Erectile Dysfunction

These manifestations can affect women and men, respectively.

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, but most often occurs in those who are non-insulin dependent (type 2 diabetes).

HHNKC is characterized by a dangerously high blood sugar that is over 600 mg/dL and is typically brought on either by an infection such as pneumonia, a urinary tract infection, or inability to effectively manage your 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 Fahrenheit)
  • 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 very dangerous condition referred to as diabetic ketoacidosis (DKA), which occurs most commonly in people who have type 1 diabetes and is often the condition that leads to the diagnosis of type 1 diabetes.

DKA is caused when the body has little or no insulin to use and, as a result, blood sugars rise to dangerous levels and the blood becomes acidic. Cell damage can occur and if it continues to progress, it can cause coma or death. DKA needs immediate medical intervention—patients with DKA will need to be monitored by a medical professional and given intravenous fluids, electrolytes, and insulin.


Frequent and long-standing 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 exacerbate heart disease and peripheral arterial disease.

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, fetal anomalies, preeclampsia (uncontrolled blood pressure in mother), fetal demise, macrosomia (large baby), hypoglycemia in babies at birth, and neonatal hyperbilirubinemia. 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)—to reduce the risk of congenital anomalies, preeclampsia, macrosomia, and other complications.

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. Those 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 think your blood sugar is elevated, 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, and 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 prior to diagnosis, so the sooner you receive treatment, the better.

For Parents of Children Without Diabetes

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 weight. If the symptoms appear to be more severe and resemble those of DKA (refer above), go to the emergency room right away.

For Parents of Children With Diabetes

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.

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
    • Frequent urination
    • Blurry vision
    • Nausea and vomiting
    • Fatigue

    People with diabetes may also feel excessive hunger, and, untreated, diabetic hyperglycemia may cause more severe symptoms.

  • 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, emotional disorders, and hormonal fluctuations.

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7 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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