• High blood sugar or hyperglycemia occurs when a person's body does not make or use the hormone insulin properly. Insulin helps the body to convert glucose from food to energy.
  • High blood sugar does not just affect people with diabetes. It can also be caused by infections, stress, inactivity and other problems.
  • Signs that you have high blood sugar include constant fatigue or thirst, chronic headaches and blurred vision.
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When you hear the term "high blood sugar," you're probably thinking of people who are diagnosed with diabetes and need insulin to keep their body in balance. High blood sugar or hyperglycemia can also affect people without diabetes. And if left untreated, it can lead to nerve damage or kidney, eye or heart disease.

High blood sugar occurs when a person's body does not produce or use properly the hormone insulin. This helps transform the food you eat into usable energy in your body. As a result, a person may feel tired all the time, be constantly thirsty, have blurred vision, or have a variety of other symptoms. These symptoms do not occur immediately and may take days or weeks if a person's blood sugar levels continue to rise, according to the Mayo Clinic.

In addition to type 1 or type 2 diabetes, infection, inactivity, stress and too much carbohydrate can lead to high blood sugar. People with cystic fibrosis and those taking beta-blockers may also be at an increased risk of developing high blood sugar levels.

To be diagnosed with high blood sugar, you need a blood test to see if your glucose level is too high. See a doctor as soon as possible if you notice any of these six signs.