How to Test Your Blood Sugar

To know if your meal plan, exercise, and medicine are controlling your blood sugar, it's important to test yourself. Maintaining your target blood sugar level is the reason for having a treatment plan, according to the American Diabetes Association.

The traditional testing method involves pricking your finger with a lancet (a small, sharp needle), putting a drop of blood on a test strip and then placing the strip into a meter that displays your blood sugar (glucose) level. Blood glucose meters and test strips are available at your local pharmacy.

Meters vary in features, readability, portability, and cost. Some meters also feature software kits that retrieve information from the meter and display graphs and charts of your past test results. Your healthcare provider can use this data to determine how your diabetes is being managed.

A newer blood sugar testing method was approved in November 1998 and features a laser to draw blood instead of traditional lancets. The laser device produces a precise beam of light that penetrates the skin on the finger instead of pricking it, reducing pain and discomfort.

In March 2001, the FDA approved the GlucoWatch, a watch-like device that helps people with diabetes measure their blood sugar via tiny electric currents. It is considered a first step toward noninvasive, continuous glucose monitoring and does have some shortfalls. The FDA emphasized, however, that the device should not replace daily fingerpricks. There are also other devices on the market, but all have their drawbacks.

When Should I Test?

Blood sugar testing is usually done before meals and at bedtime. Relying only on a before-breakfast blood sugar test isn't sufficient. Instead, a random sampling of blood sugar testing before breakfast, before dinner and at bedtime is most helpful. Your healthcare provider will tell you when and how often you should check your blood sugar.

Note: Remember that being sick complicates your diabetes. You may need to test your blood sugar more frequently.

The chart below gives you an idea of where your blood sugar level should be. Your ideal blood sugar range may be different from another person's and will change throughout the day.

When Should I Call My Doctor?

In most cases, fasting blood sugar more than 180 mg/dL is too high and blood sugar less than 70 mg/d/L is too low. If your blood sugar is less than 70 mg/dL and you have more than one unexplained low blood sugar reaction a week, call your doctor.

If your blood sugar is greater than 180 mg/dL for more than a week or if you have two consecutive readings greater than 300 mg/dL, call your doctor.

In most cases, your doctor will suggest changes in your diabetes management plan.

How Do I Record My Test Results?

Keep good records of any blood, urine, or ketone tests you do. Your records can help alert you to any problems. Also, these test records help your doctor make any needed changes in your meal plan, medicine, or exercise program. Bring these records with you every time you visit your doctor.

Next: Urine Tests >

Reviewed by the Department of Endocrinology and Department of Patient Education and Health Information at The Cleveland Clinic.