Hyperglycemia Complications: Identifying the Underlying Cause

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Hyperglycemia occurs when there is too much sugar or glucose in the bloodstream. It is often associated with diabetes mellitus. Typically, hyperglycemia is a result of insulin deficiency, insulin resistance, or a combination of both.

However, people who do not have diabetes can also experience hyperglycemia. It’s usually caused by another underlying medical condition, stress (like surgery or trauma), or by certain medications.

Here is an overview of what you should know about acute and chronic hyperglycemia.

Person checking her blood sugar

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Who Is At Risk?

About 1.5 million Americans are diagnosed with diabetes each year, which puts them at risk of developing hyperglycemia.

According to the American Diabetes Association (ADA), diabetes continues to impact seniors over age 65, as well as Asian Americans, Hispanics, non-Hispanic Blacks, and American Indians/Alaskan Natives at higher rates than other ages and racial/ethnic groups.

Family History and Genetics

Having a family member with diabetes also increases your risk of developing diabetes. While there seems to be a genetic predisposition to all forms of diabetes, just because someone in your family has diabetes does not mean that you will get it.

The ADA states that while type 2 diabetes has a stronger link to family history than type 1 diabetes, environmental and behavioral factors also play a role. There are interventions that can help prevent or delay a diabetes diagnosis.


Medication use can also contribute to high blood sugar. For example, prolonged use of medications such as steroids can increase the risk of developing high blood sugar.

Health Conditions

Certain health conditions other than diabetes can increase a person’s risk of hyperglycemia. For example, people with Cushing’s syndrome and polycystic ovarian syndrome (PCOS) are at an increased risk of developing hyperglycemia because of increased insulin resistance.

Other health-related factors that can increase the risk of developing diabetes include age, weight, and cardiovascular risk factors, such as metabolic syndrome, heart disease, and a sedentary lifestyle.

Surgery, trauma, and infections are other instances in which a person is at an increased risk of developing high blood sugar.

Identifying Symptoms and When to Be Concerned

The most common symptoms of hyperglycemia include excessive thirst, hunger, and urination.

However, in the case of diabetes—specifically, type 2 diabetes—people may not have symptoms for many years. In fact, the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) estimates that 7.3 million adults ages 18 and older have diabetes but are undiagnosed—about 21.4% of adults with diabetes.

Screening for diabetes, particularly in at-risk populations, is essential to diagnosing and treating the condition.

The ADA recommends routine screenings for type 2 diabetes for everyone every three years after age 35, and more frequently if symptoms develop or risks change (i.e., weight gain). Routine screenings may be recommended by your healthcare provider if you're under 35 but have certain high-risk factors, like being overweight or obese, a family history of the disease, heart disease, high blood pressure, a history of gestational diabetes, and/or a sedentary lifestyle.

Common Symptoms

Some of the more common symptoms of hyperglycemia that may develop over several days or weeks include:

  • Numbness and tingling in the hands and feet
  • Dry mouth, thirst
  • Dry, itchy skin
  • Frequent infections such as yeast infections or infections of the oral cavity
  • Acanthosis nigricans (dark “velvety” skin patches on armpits, groin, neck folds, and over the joints of fingers and toes—seen most often in African-Americans and people with prediabetes or type 2 diabetes)
  • Fatigue
  • Wounds that are slow to heal
  • Rapid heartbeat
  • Confusion
  • Irritability
  • Blurred vision
  • Weight loss (most common in type 1 diabetes, but can occur in type 2 diabetes that has gone undetected for a long time)
  • Bedwetting (more common in kids with type 1 diabetes)

Serious Symptoms

Acute complications of high blood sugars, such as diabetic ketoacidosis (more common in people with type 1 diabetes) or hyperglycemic hyperosmolar nonketotic syndrome (more common in people with type 2 diabetes) may also occur. If not treated right away, these complications can result in coma or death.

Diabetic ketoacidosis typically occurs quickly and is characterized by hyperglycemia, elevated ketones, and metabolic acidosis. If a person has the following symptoms of diabetic ketoacidosis, they need emergency medical care:

  • Fruity breath
  • Nausea
  • Vomiting
  • Abdominal pain
  • Rapid, shallow breathing


Having a random blood sugar level that is elevated after a large carbohydrate meal or during an illness or stressful day is not necessarily a reason to panic. However, having consistently elevated blood sugars can cause acute and chronic complications.

Excess blood sugar can affect the small and large vessels in the body, which increases the risk of developing complications of the eyes, heart, nerves, kidneys, and brain.

If you have diabetes and are having elevated blood sugars regularly, you should talk to your doctor about your treatment. If you do not have diabetes but are experiencing symptoms and have risk factors for the condition, it’s important to let your doctor know.

People with Diabetes: Acute Hyperglycemia

Acute hyperglycemia can be addressed through diabetes self-management education and making changes to your treatment plan.

There are many causes of acute hyperglycemia, including medication mistakes, too many carbohydrates, weight gain, lack of exercise, illness, and stress.


Acute hyperglycemia can happen if you are not matching your medication to your meals, you miss a dose of medication, you are not on the right kind of medication, you are receiving an incorrect dosage, or you are using an improper injection technique (if you are on insulin or non-insulin injectables).

For example, for people with diabetes who take insulin, simply rotating injection sites or avoiding lumpy areas may help to reduce their blood sugars.

If you are currently experiencing hyperglycemia and have been taking your medication as directed, your doctor might suggest a different type of medication or a higher dose (if needed).

Carbohydrate Intake

Carbohydrates get broken down into glucose and are the body’s preferred source of energy. Most people with diabetes need to modify their intake of carbohydrates to keep their blood sugars from getting too high.

Acute hyperglycemia can happen if you are eating too many carbohydrates at a meal. In this case, reducing carbohydrates at the next meal may help to lower your blood sugar levels.

If you are having trouble figuring out which foods are triggering your blood sugars, make an appointment to meet with a registered dietitian (RD) or certified diabetes care and education specialist (CDCES).

Weight Gain

Gaining weight can increase insulin resistance in people with diabetes, which in turn can increase the risk of high blood sugars.

Lack of Physical Activity

If you have diabetes and are typically active, then reducing your physical activity can result in an increase in blood sugars.

Exercise helps to lower blood sugar by increasing insulin sensitivity. When cells are sensitive to insulin, glucose can be taken from the bloodstream to the cells to use for energy.


Elevated blood sugars can lead to pancreatitis. There seems to be a correlation between diabetes and pancreatitis, which might be related to insulin resistance and elevated blood sugars.

Illness and Stress

Being sick or stressed increases blood sugars by activating cortisol, which increases insulin resistance. People with type 1 diabetes need to work with their doctor to develop a “sick day regimen” to help prevent their blood sugars from going too high.

People with type 1 diabetes sometimes think that they should avoid taking insulin when they are sick because they are not eating or having gastrointestinal issues. However, this is not advised as insulin omission can lead to diabetic ketoacidosis.

If you are ill, make sure that you let your doctor know. They will be able to guide you on how to adjust your insulin, test for ketones, and stay hydrated.

People With Diabetes: Chronic Hyperglycemia

Chronically elevated blood sugars can lead to complications of the eyes, heart, kidneys, nerves, and brain.


Prolonged periods of hyperglycemia can damage the small vessels in the eye, ultimately leading to diabetic retinopathy.

Diabetic retinopathy can begin to occur even before a diabetes diagnosis, which is one reason why the ADA recommends that all people newly diagnosed with type 2 diabetes receive a dilated eye exam shortly after they are diagnosed.

Adults with type 1 diabetes should have an eye examination within five years of being diagnosed. Caregivers of children with type 1 diabetes should ask their child’s pediatrician when and how often an eye exam is needed.


Nephropathy is the medical term for kidney disease. High blood sugars can damage the vessels in the kidneys and prevent them from being able to filter waste products. The inability to filter properly results in protein building up and spilling into the urine (microalbuminuria).

If caught early, kidney disease can be treated and further damage prevented. However, long-standing kidney disease accompanied by high blood pressure and high blood sugar may lead to end-stage renal disease (ESRD), which can lead to the need for dialysis or a kidney transplant.

Cardiovascular Disease

Cardiovascular disease is the number one cause of death in people with diabetes. Some types of heart disease include atherosclerosis (hardening of the arteries), arrhythmias, and heart failure.

People with poorly controlled diabetes who are overweight, have a family history of heart disease, and have high blood pressure, elevated cholesterol, and high triglycerides are at increased risk of developing heart disease.


Elevated blood sugars can lead to nerve damage all over the body. Some common types of nerve damage include peripheral neuropathy, gastroparesis, and autonomic neuropathy.

Neuropathy (particularly peripheral neuropathy) can be painful and increases a person’s risk of developing skin infections.


According to the ADA’s Standards of Care, “People with diabetes have higher incidences of all-cause dementia, Alzheimer’s disease, and vascular dementia than people with normal glucose tolerance.”

However, the increased incidence may not be limited to people with diabetes. Some studies have shown that high blood glucose levels in people with and without diabetes increase the risk of dementia.

In a prospective, community-based cohort study of 2,067 participants, researchers found that higher glucose levels were associated with an increased risk of dementia in populations without and with diabetes.

More research is needed to determine the relationship between high blood sugars and cognitive impairment in people without diabetes.

Complications of High Blood Sugars for People Who Don’t Have Diabetes

When blood sugars are elevated for an extended time, it can damage blood vessels and organs.

If you have hyperglycemia that is caused by something other than diabetes, getting your sugars under control can prevent you from developing prediabetes or diabetes, and can also reduce your risk of developing complications.

Certain conditions, situations, and medications can increase the risk of high blood sugar in people without diabetes. Some contributing factors include:

  • Cushing’s syndrome
  • Polycystic ovarian syndrome
  • Cystic fibrosis
  • Pancreatic diseases
  • Surgery and stress
  • Trauma
  • Medications
  • Being overweight or obese
  • Lifestyle factors (e.g., sedentary behavior, poor diet, and smoking)

A Word From Verywell

High blood sugar, or hyperglycemia, is usually linked to prediabetes and diabetes mellitus. If you have diabetes and are experiencing high blood sugars, it’s important to discuss your treatment plan with your doctor.

Adjusting your regimen can help you maintain adequate blood glucose control and delay or prevent diabetes complications. It can also help to prevent an emergency hyperglycemic event, such as diabetic ketoacidosis.

If you have not been diagnosed with diabetes, but think that you are having symptoms of high blood sugar, such as increased urination and fatigue, ask your doctor if you should be tested for hyperglycemia.

High blood sugar is not always related to diabetes. It can also happen if you have surgery, have another health condition, or after a traumatic event.

13 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 registered dietitian and certified diabetes care and education specialist.