Monitoring: When and Why to Test Blood Sugar

Monitoring and recording blood sugar (glucose) levels gives you valuable information for controlling your diabetes. Checking blood sugar regularly and understanding the results will help you and your health care team adjust your treatment plan as needed.

Keeping your blood sugar in the recommended target range can prevent or delay the long-term health problems caused by diabetes. You can best manage your diabetes by keeping track of your blood glucose numbers using a blood glucose meter and with the results of your A1C (pronounced a-one-c) tests — a long-term measure of blood sugar levels in your body.

Blood Sugar (Glucose)

The targets recommended by the American Diabetes Association® are listed below. Work with your physician or certified diabetes educator to set your personal targets.

Many people use their meter to check their blood sugar several times a day. Talk with your physician or certified diabetes educator about when and how often to check your blood glucose.

While each person’s blood sugar testing schedule is slightly different, many people test at common points during the day. As always, consult your health care team about your schedule and directions for testing. Here are some examples of when people commonly test:

1. Fasting blood sugar testing: This test is done in the morning upon waking, before eating or drinking anything, before exercising, and before taking oral antihyperglycemic medications or insulin.

2. Pre-meal testing: Some people test their glucose just before eating, especially if they use short-acting insulin or pre-meal medication to control glucose. Work with your health care team to determine how to interpret and use these numbers.

3. Postprandial, or after-meal, testing: This is commonly done one to two hours after a meal. This gives your physician/health care team a good idea of how well your medications are working to control blood glucose.

4. Bedtime testing: Work with your health care team to determine the best time for this test.

Keep a log on paper or use the personal blood glucose tracker on this site. Reviewing your records can show you patterns and indicate times of day when you should fine-tune your diabetes control plan.

What can make blood glucose rise?

• A meal or snack with more food or carbohydrates than usual

• Inactivity

• Not enough diabetes medication

• Side effects of other medications

• Infection or other illness such as a cold or the flu

• Changes in hormone levels, such as during menstrual periods

• Stress

What can make blood glucose fall?

• A meal or snack with less food or fewer carbohydrates than usual

• Drinking alcoholic beverages

• Missing a meal or snack

• Extra activity

• Too much diabetes medication

• Side effects of other medications

Hemoglobin A1C

Hemoglobin A1C (pronounced a-one-c) is also known as HbA1C or just A1C. On this web site we refer to it as A1C.

A1C is a test that provides information about your average blood sugar level over a period of approximately 2-3 months. To obtain this information, your physician takes a sample of your blood and sends it to a laboratory for testing. It is recommended to have your A1C checked twice a year.

A1C is represented as a percent. The higher the percent, the more sugar that has been in the blood over time.

The American Diabetes Association recommends that people with diabetes have an A1C of 7 percent or less.

Although A1C is a measure of long-term blood glucose control, it still reflects your average daily blood glucose levels. To help you see this relationship, you can use the chart below: