- Things to Know
- 10 Symptoms
- Risks and Complications
Things to know about high blood sugar (hyperglycemia)
- Low high blood sugar (hyperglycemia) is abnormally high blood levels of insulin in the blood. Hyperglycemia is a hallmark sign of diabetes (both type 1 diabetes and type 2 diabetes) and prediabetes, and diabetes is the most common cause of it. Severely elevated glucose levels can result in a medical emergency like diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar nonketotic syndrome (HHNS, also referred to as hyperglycemic hyperosmolar state).
- The primary symptom of hyperglycemia is excessive amounts of sugar (glucose) in the urine. Other symptoms and signs of high blood sugar levels in the blood are blurred vision, hunger ("hangry"), and headaches.
- Other conditions that can cause high blood sugar are pancreatitis, Cushing's syndrome, unusual hormone-secreting tumors, pancreatic cancer, certain medications, and severe illnesses.
- Insulin is the treatment for people with type 1 diabetes, and life-threatening increases in glucose levels. People with type 2 diabetes may be managed with a combination of different oral and injectable medications. Hyperglycemia due to medical conditions other than diabetes is generally treated by treating the underlying condition responsible for elevated glucose.
What is high blood sugar?
Hyperglycemia is the medical term describing an abnormally high blood glucose (blood sugar) level. Blood sugar is measured in a sample of blood taken from a vein or a small finger stick sample of blood. It can be measured in a laboratory either alone or with other blood tests, or it can be measured using a handheld glucometer, a small device that allows frequent monitoring of blood glucose levels without the need for a doctor's office or laboratory.
Hyperglycemia or high blood sugar is a hallmark sign of diabetes (both type 1 diabetes and type 2 diabetes) and prediabetes. Normal ranges for blood glucose measurements can vary slightly among different laboratories, but in general, a fasting (early a.m. before breakfast) glucose level is considered normal if it is between 70-100 mg/dL. Glucose levels may rise slightly above this range following a meal. Random blood glucose measurements are usually lower than 125 mg/dL.
|Result*||A1C Test||Fasting Blood Sugar Test||Glucose Tolerance Test||Random Blood Sugar Test|
|Diabetes||6.5% or above||126 mg/dL or above||200 mg/dL or above||200 mg/dL or above|
|Prediabetes||5.7 – 6.4%||100 – 125 mg/dL||140 – 199 mg/dL||N/A|
|Normal||Below 5.7%||99 mg/dL or below||140 mg/dL or below||N/A|
*Results for gestational diabetes can differ.
10 Symptoms and signs of high blood sugar
The main symptoms of hyperglycemia are increased thirst and a frequent need to urinate.
Other symptoms that can occur with high blood sugar are:
- Blurred vision.
- The trouble with thinking or concentrating.
- Frequent urination
Other symptoms and signs of high blood sugar include:
- Sunburns. Pain from a sunburn causes pain, which increases blood sugars.
- Coffee. Some people with diabetes have an extra sensitivity to caffeine.
- Gum disease. Gum disease is a complication of diabetes and can make blood sugars rise.
- Losing sleep. Going a night or two without sleeping can cause the body to use insulin less efficiently.
Nose spray. Some nasal sprays have chemicals that trigger the liver to make more blood sugar.
Severely elevated blood sugar levels can result in a medical emergency ("diabetic coma"). This can occur in both people with type 1 and those with type 2 diabetes. People with type 1 diabetes may develop diabetic ketoacidosis (DKA), and those with type 2 diabetes can develop hyperglycemic hyperosmolar nonketotic syndrome (HHNS, also referred to as hyperglycemia hyperosmolar state). These so-called hyperglycemia crises are serious conditions that can be life-threatening if not treated immediately. Hyperglycemic crises cause about 2,400 deaths each year in the U.S.
Over time, hyperglycemia can lead to damage to organs and tissues. Long-term hyperglycemia can impair the immune response, leading to poor healing of cuts and wounds. It can also cause nerve damage, vision problems, and damage to the blood vessels and kidneys (see below).
What causes high blood sugar?
A number of medical conditions can cause hyperglycemia, but the most common by far is diabetes mellitus. Diabetes affects over 8% of the total U.S. population. In diabetes, blood glucose levels rise either because there is an insufficient amount of insulin in the body or because the body cannot use insulin well. Normally, the pancreas releases insulin after a meal so that the cells of the body can utilize glucose for fuel. This keeps blood glucose levels in the normal range.
Type 1 diabetes is responsible for about 5% of all cases of diabetes and results from damage to the insulin-secreting cells of the pancreas. Type 2 diabetes is far more common and is related to the body's inability to effectively use insulin. In addition to type 1 and type 2, gestational diabetes is a form of diabetes that develops in pregnant women. Studies show that between 2% to 10% of all pregnant women get gestational diabetes.
Sometimes, high blood sugar is not the result of diabetes. Other medical conditions that can cause the condition include:
- Pancreatitis (inflammation of the pancreas)
- Pancreatic cancer
- Hyperthyroidism (overactive thyroid gland)
- Cushing's syndrome (elevated blood cortisol level)
- Unusual tumors that secrete hormones, including glucagonoma, pheochromocytoma, or growth hormone-secreting tumors
- Severe stresses on the body, such as heart attack, stroke, trauma, or severe illnesses, can temporarily lead to hyperglycemia
- Taking certain medications, including prednisone, estrogens, beta-blockers, glucagon, oral contraceptives, phenothiazines, and others, can elevate blood glucose levels
How is high blood sugar diagnosed?
There are different kinds of blood tests that can diagnose hyperglycemia. These include:
- Random blood glucose: this test reflects the blood sugar level at a given point in time. Normal values are generally between 70 and 125 mg/dL, as discussed earlier.
- Fasting blood glucose: This is a measurement of blood sugar level taken in the early morning before eating or drinking anything since the night before. Normal fasting blood glucose levels are less than 100 mg/dL. Levels above 100 mg/dL up to 125 mg/dL suggest prediabetes, while levels of 126 mg/dL or above are diagnostic of diabetes.
- Oral glucose tolerance test: this is a test that measures blood glucose levels at given time points after a dose of sugar is consumed. This test is most commonly used to diagnose gestational diabetes.
- Glycohemoglobin A1c: is a measurement of glucose that is bound to red blood cells and provides an indication of blood sugar levels over the past 2 to 3 months.
What is the treatment for high blood sugar?
Mild or transient hyperglycemia may not need medical treatment, depending upon the cause. People with mildly elevated glucose or prediabetes can often lower their glucose levels by incorporating diet and lifestyle changes. Discuss any dietary or lifestyle changes with your healthcare team to assure or use reliable resources such as the American Diabetes Association.
Insulin is the treatment of choice for people with type 1 diabetes and life-threatening increases in glucose levels. People with type 2 diabetes may be managed with a combination of different oral and injectable medications. Some people with type 2 diabetes also take insulin.
High blood sugar due to medical conditions other than diabetes is generally treated by addressing the underlying condition responsible for elevated glucose. In some cases, insulin may be needed to stabilize glucose levels during this treatment.
What are the dangers and complications of high blood sugar?
Long-term complications of prolonged hyperglycemia or high blood sugar can be severe. These occur in people with diabetes and are worse when the condition is poorly controlled. The long-term complications of diabetes tend to develop slowly over time.
Some of the complications of hyperglycemia in poorly controlled diabetes are:
- Heart and blood vessel disease can increase the risk of heart attack, stroke, and peripheral artery disease
- Poor kidney function eventually leads to kidney failure
- Nerve damage can lead to burning, tingling, pain, and changes in sensation
- Eye diseases, including damage to the retina, glaucoma, and cataracts
- Gum disease
CDC.gov. About Diabetes. Updated: Jun 01, 2017.
American Diabetes Association.
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People with diabetes can manage and prevent low or high blood sugar levels (hyperglycemia or hypoglycemia) by keeping a log of your blood sugar levels when you are eating and fasting and eat foods that are high in carbohydrates and sugar, for example, buttered potatoes, candy, sugary desserts, and fatty foods.
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Extremely high levels of blood glucose in the blood can be dangerous and life threatening if you have type 1, type 2, or gestational diabetes.
If you or someone that you are with has extremely high blood glucose levels, call 911 or go to your nearest Urgent Care or Emergency Department immediately.
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