Blood glucose (blood sugar) targets

The American Diabetes Association recommends the following targets for most non-pregnant adults with diabetes. More or less stringent blood sugar targets may be appropriate for each individual, so your doctor or diabetes educator may recommend different targets.

    • Before a meal (pre-prandial) glucose: 80–130 mg/dl
    • 1-2 hours after beginning of the meal (postprandial) plasma glucose: Less than 180 mg/dl


How often should blood sugars be checked?

People with type 1 diabetes usually need to measure their blood glucose levels at least four times a day. People with type 2 diabetes who take insulin or other diabetes medications also need to measure their glucose levels regularly, according to their doctor’s recommendation. 

Accuracy of blood sugar readings

The accuracy of fingerstick glucose readings depends on many factors

    • The quality of the meter (see glucose meter accuracy standards below). All meters should meet the FDA standard, but some actually fail accuracy standards when tested by independent organizations. If you are concerned about the accuracy of your meter brand, ask your doctor. 
    • The quality of the test strips. Always use new test strips that are authorized for sale in the United States. Do NOT use previously owned test strips or test strips that are not authorized for sale in the United States. These strips are often expired or highly inaccurate. 
    • How well you perform the test. For example, you should wash and dry your hands before testing to ensure there are no interfering substances. 
    • Your hematocrit (the amount of red blood cells in the blood). If you are severely dehydrated or anemic, your test results may be less accurate. 
    • Interfering substances. (examples include Vitamin C, Tylenol, and uric acid) Check the instructions for your meter and test strips to find out what substances may affect the testing accuracy.
    • Altitude, temperature, and humidity (High altitude, low and high temperatures, and humidity can cause unpredictable effects on glucose results). 
    • Proper storage of the meter and strips. It is important to store test strip vials closed. The test strips that come with the machine can give inaccurate readings if they’re stored in locations that are too hot, cold, or are expired. It’s important to store the test strips as carefully as you would any medication.

Glucose meter accuracy standards

When you check your blood glucose, the reading on the meter is telling you approximately what your blood sugar is. Some meters are more accurate than others (sometimes by a large margin). The FDA’s guidelines are that meter readings must be accurate to within 15% of the true glucose value, 95% of the time, and accurate within 20% of the true glucose value 99% of the time. 

Let’s consider a theoretical example to demonstrate what this means. Imagine that your blood glucose level was 100, and you did 100 fingersticks to check your blood sugar. A meter with the accuracy described above would give you:

    • 95 readings that would be between 85 – 115 (this is +/- 15% of the true glucose level) 
    • 4 readings would be between 80 – 120 (this is +/- 20% of the true glucose level)
    • 1 reading would be either lower than 80 or higher than 120 (1% of readings are outside of the 20% window)