Causes and Risk Factors of Hyperglycemia (High Blood Glucose)

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There are a host of reasons a person might develop hyperglycemia (high blood glucose). 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
© Verywell, 2018


The overarching cause of hyperglycemia is a problem with insulin. Insulin is the hormone produced by the pancreas that 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 has nowhere to go and so it 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


The role of genetics in hyperglycemia is easiest explained in the context of diabetes risk based on family history. According to the ADA, "diabetes does not seem to be inherited in a simple pattern. Yet clearly some people are born more likely to develop diabetes than others." The similarity between the two 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. Some common environmental factors that have been linked to type 1 diabetes are cold weather, viruses, and what a person's early diet was (it's less common in people who were breastfed and who ate solids later than usual). In studies, researchers have also noted that people who developed diabetes late in life had 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 part 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. These lifestyle risk factors are commonly associated with type 2 diabetes:

  • 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, the glucose will 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 U.S. Centers for Disease Control and Prevention, people who light up regularly are 30 percent to 40 percent more likely to develop type 2 diabetes than non-smokers. 
  • Pregnancy. Women who develop gestational diabetes while expecting are at an increased risk of prediabetes and type 2 diabetes later. Having a baby who weighs over nine pounds also ups a woman's risk of diabetes. 
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