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What Are the Causes of High Glucose Blood Test Results?

author image Chad Stone
Chad Stone is a medical scientist based in the Pacific Northwest. Since 2003, Dr. Stone has has published high-profile articles on the molecular mechanisms of cardiovascular disease and cancer in journals such as Blood and the Journal of the American Heart Association. Dr. Stone is a specialist in blood biology as well as cancers of breast, colon, kidney and other tissues.
What Are the Causes of High Glucose Blood Test Results?
Medical person taking blood from patient's finger Photo Credit: hxdbzxy/iStock/Getty Images

High blood glucose may be the signal of a developing medical condition or may simply be a short-term response to recent eating or stress. Diabetes, including gestational diabetes associated with pregnancy, is a prevalent cause of high blood glucose test results. High blood glucose levels can also indicate thyroid disease or pancreatic inflammation. Certain medications can cause your blood glucose levels to spike as well.

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Eating Before Your Blood Test

Woman eating a sandwich
Woman eating a sandwich Photo Credit: DAJ/amana images/Getty Images

If you forget to fast prior to a fasting blood glucose test, high glucose levels may be caused by the normal rise in blood sugar that occurs after eating. If you are given a blood glucose test after eating, be sure to alert your physician, who may suggest a follow-up test to ensure proper testing conditions.


Diabetic woman checking her blood with a glaucometer
Diabetic woman checking her blood with a glaucometer Photo Credit: Purestock/Purestock/Getty Images

High blood glucose levels are the hallmark of type 1 and 2 diabetes. They occur in the early stages of these conditions, before other symptoms appear. Diabetes specific to pregnancy, or gestational diabetes, also causes an increase in blood sugar levels. To best diagnose prediabetes or diabetes, your doctor will likely order follow-up glucose tests on different days. She may also recommend an oral glucose tolerance test, in which your blood glucose levels are measured before and after consuming a sugar-containing drink. You will also likely undergo a hemoglobin A1c test, which serves to measure your average blood sugar levels over the past few months.

Drugs and Medical Conditions

Close-up of a doctor prescribing a prescription bottle.
Close-up of a doctor prescribing a prescription bottle. Photo Credit: Jupiterimages/Stockbyte/Getty Images

Apart from diabetes, a large number of less common medical conditions can also cause high blood glucose levels. Such conditions include an overactive thyroid gland, pancreatic inflammation and certain cancers. Higher-than-normal blood sugar levels may also be caused by infections, especially if they are severe. Certain medications, notably corticosteroids, can raise blood glucose levels as well. Others, such as some psychiatric medications, may increase the risk of developing diabetes over time.

Stress and Trauma

Stressed businessman squinting his eyes
Stressed businessman squinting his eyes Photo Credit: Comstock Images/Stockbyte/Getty Images

Psychological stress and physical trauma are other triggers for increased blood sugar levels. If you were recently injured or have had a recent shocking life event, your blood sugar levels may be temporarily elevated. Along these lines, stress-induced increases in blood glucose are frequently seen in people admitted to intensive care units.

Talk to Your Doctor

Doctor talking to his patient
Doctor talking to his patient Photo Credit: Thinkstock Images/Stockbyte/Getty Images

If you have a high blood glucose test result, talk to your doctor, and learn what the next steps should be. In some cases, high blood glucose levels may occur only temporarily. Otherwise, however, the most common explanation for elevated blood glucose is diabetes. And untreated, high blood glucose levels over time can damage vital organs and promote heart disease and strokes.

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