Causes and Risk Factors of Hyperglycemia (High Blood Glucose)

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There are a host of reasons a person might develop high blood glucose, a condition known as hyperglycemia.

For someone who has diabetes, it could be a problem with their treatment or management plan. In the case of an otherwise healthy person, lifestyle factors such as weight gain, too little activity, or smoking could play a role in bumping up blood sugar levels. Pregnancy can also be a risk factor. And everyone experiences increases in blood sugar levels during the early morning.

hyperglycemia causes and risk factors

Insulin Issues

The overarching cause of hyperglycemia is a problem with insulin. This hormone is produced by the pancreas and controls the levels of glucose, or sugar, in the blood.

When the body digests carbohydrates, it breaks them down into sugar molecules. Glucose is one of these. Glucose is absorbed directly into the bloodstream, but it needs the help of insulin to get into cell tissues to provide them with fuel.

If the body isn't producing any insulin or enough insulin, glucose builds up in the blood.

According to the American Diabetic Association (ADA), there are a number of reasons this might happen: 

  • If you have type 1 diabetes, you may not have given yourself enough insulin during a routine self-injection. 
  • If you use an insulin pump to manage type 1 diabetes, the pump could be malfunctioning.
  • If you have type 2 diabetes, an increase in blood sugar could mean that even though there's plenty of insulin, it's not as effective as it should be.
  • You're otherwise healthy, but experience a bout of high blood sugar in response to eating too much, not getting enough exercise, or stress (from an illness or a personal issue), which affect hormone levels.
  • You experience a surge of hormones produced by the body around 4 a.m. to 5 a.m. known as the dawn phenomenon
Insulin helps transport glucose from the bloodstream with the help of glucose transporters.


The role of genetics in hyperglycemia is best explained in the context of diabetes risk based on family history. The ADA notes that diabetes doesn't seem to be inherited in a simple pattern. Still, some people are born more likely to develop diabetes than others. The similarity between type 1 and type 2 diabetes is that something in your environment triggers a predisposition to the disease. 

In the case of type 1 diabetes, which occurs when the pancreas doesn't produce enough insulin, you need to inherit risk factors from both of your parents before something in your environment is able to trigger it.

Common environmental factors that have been linked to type 1 diabetes include cold weather, viruses, and a person's diet early in life. It's less common in people who were breastfed and ate solids later than usual.

Researchers have also noted people who develop diabetes late in life have certain autoantibodies in their blood.

Type 2 diabetes is different from type 1 in that the body becomes resistant to insulin. Research has found that genetics play a more significant role in type 2 diabetes than in type 1 diabetes, but lifestyle habits also factor in.


Daily habits play a much larger role in type 2 diabetes than in type 1 diabetes. Lifestyle risk factors commonly associated with type 2 diabetes include:

  • Being overweight or obese: Body fat increases the resistance of cells to insulin.
  • Not exercising enough: Glucose is the fuel the body needs to function. The body burns it just like a car burns gasoline. If a person is not active enough to burn off all the glucose that builds up in the blood from eating carb-rich foods, glucose can accumulate to unhealthy levels.
  • High blood pressure: If your blood pressure is over 140/90, you may be at an increased risk of type 2 diabetes. 
  • Abnormal cholesterol and triglyceride levels: Not enough high-density lipoprotein (HDL) cholesterol and high levels of triglycerides, a type of fat, increase the risk of type 2 diabetes. 
  • Age: Your risk increases as you get older and if you become less active, lose muscle mass, and gain weight, which can tend to happen with age.
  • Smoking: According to the Centers for Disease Control and Prevention (CDC), people who light up regularly are 30% to 40% more likely to develop type 2 diabetes than non-smokers. 
  • Pregnancy: Women who develop gestational diabetes are at an increased risk of prediabetes and type 2 diabetes later. Having a baby who weighs over 9 pounds also ups a woman's risk of diabetes. 

Frequently Asked Questions

  • What causes hyperglycemia other than diabetes?

    Pancreatic disease (pancreatitis, pancreatic cancer, and cystic fibrosis) and endocrine disorders such as Cushing syndrome can cause hyperglycemia, which means high blood sugar. Surgery or injuries that trigger a stress response in the body can also cause it. Pregnant women may develop hyperglycemia in the form of gestational diabetes, and certain medications can raise blood sugar.

  • Why do patients sometimes get hyperglycemia while in the hospital?

    Following trauma or during an illness, blood glucose levels may rise due to stress on your body. When it’s temporary, this type of stress-induced hyperglycemia can actually help your body heal because it fuels the immune system. If high blood sugar persists, though, it can cause problems and needs to be treated.

  • How can I lower my risk of hyperglycemia?

    Following a hyperglycemic diet, exercising regularly, and managing your weight are the best ways to reduce your risk of hyperglycemia and diabetes. Smoking increases your risk, so avoid that as well.

8 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.
  1. American Diabetes Association. Hyperglycemia (high blood glucose).

  2. American Diabetes Association. Learn the genetics of diabetes.

  3. Zaharieva ET, Velikova TV, Tsakova AD, et al. Prevalence of positive diabetes-associated autoantibodies among type 2 diabetes and related metabolic and inflammatory differences in a sample of the bulgarian populationJ Diabetes Res. 2017;2017:9016148. doi:10.1155/2017/9016148

  4. National Institute of Diabetes and Digestive and Kidney Diseases. Risk factors for type 2 diabetes.

  5. American Heart Association. Understand your risk for diabetes.

  6. Centers for Disease Control and Prevention. Smoking and diabetes.

  7. Cleveland Clinic. Hyperglycemia (high blood sugar).

  8. Di Luzio R, Dusi R, Mazzotti A, et al. Stress hyperglycemia and complications following traumatic injuries in individuals with/without diabetes: The case of orthopedic surgery. Diabetes Metab Syndr Obes. 2020;13:9-17. doi:10.2147/DMSO.S225796

By Debra Manzella, RN
Debra Manzella, MS, RN, is a corporate clinical educator at Catholic Health System in New York with extensive experience in diabetes care.