Before you had diabetes, no matter what you ate or how active you were, your blood glucose (sugar) levels stayed within a normal range. But with diabetes, your blood glucose level can rise higher, and some diabetes medications can make them go lower than normal. Many factors can change your blood glucose levels. Learning about these factors can help you control them.

You can use your blood glucose levels to make decisions about food and activity. These decisions can help you delay or prevent diabetes complications such as heart attack, kidney disease, blindness, and amputation. Keeping your diabetes ABCs on track is the most effective way to prevent diabetes-related health problems.

  • Too much food, such as a meal or snack with more carbohydrates than usual

  • Not being active

  • Not enough insulin or oral diabetes medications

  • Side effects from other medications, such as steroids or antipsychotic medications

  • Illness—your body releases hormones to fight the illness, and those hormones raise blood glucose levels

  • Stress, which can produce hormones that raise blood glucose levels

  • Short- or long-term pain, such as pain from a sunburn—your body releases hormones that raise blood glucose levels

  • Menstrual periods, which cause changes in hormone levels

  • Dehydration

  • Not enough food, such as a meal or snack with fewer carbohydrates than usual or a missed meal or snack

  • Alcohol, especially on an empty stomach

  • Too much insulin or oral diabetes medications

  • Side effects from other medications

  • More physical activity or exercise than usual—physical activity makes your body more sensitive to insulin and can lower blood glucose

There are two ways to keep track of your blood glucose levels:

  • Using a blood glucose meter to measure your blood glucose level at that moment

  • Getting an A1C test at least twice a year to find out your average blood glucose for the past 2 to 3 months

This hand-out was published in Clinical Diabetes, Vol. 36, issue 2, 2018, and was adapted from the American Diabetes Association’s Diabetes Advisor handout “Factors Affecting Blood Glucose.” Visit the Association’s Patient Education Library at for hundreds of free, downloadable handouts in English and Spanish. Distribute these to your patients and share them with others on your health care team. Copyright American Diabetes Association, Inc., 2018.

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