How long should you fast before checking your blood sugar

Understand Diabetes Testing

If you have diabetes, it's imperative that you learn to effectively self-test your blood sugar to keep your glucose levels in check. For example, results from a study of more than 5,000 people living with diabetes showed that even those people who don't take medication for diabetes have better blood sugar control if they test regularly. The study participants' risk of early kidney damage, strokes, and death from diabetes-related causes was also reduced by one-third.

Of course, the accuracy of your results is tied to the accuracy of your checking — and to your understanding of what all the numbers mean. "The most important point to me is that people are learning something from checking their blood sugar," says Sacha Uelmen, RDN, CDE, director of nutrition for the American Diabetes Association. "Don't just look at those numbers, write them down, and move on. If you have diabetes, take an active role in your health." To get the most useful readings, learn these common blood sugar testing mistakes and how to avoid them.

Testing Your Fingertip

"The single biggest mistake people make is testing the fingertip where the nerves are located," says Renee Amori, MD, assistant professor of medicine in the division of endocrinology at Drexel University College of Medicine in Philadelphia. The pad of your finger is the most sensitive spot, so testing there will hurt.

The solution for better diabetes control: Put your hands together with flat palms and fingertips pressed together. Test along the edges that are now visible. "Testing on the edges is going to be less painful because you're not going to be touching things with them," Uelmen says.

Cleaning Fingers Incorrectly

"Don't use alcohol on your fingertips because the drying action of the alcohol can hurt," says Dr. Amori. Other mistakes people make are licking their fingers to get out a test strip and not cleaning their fingers at all. Whatever was in your mouth or whatever you just touched is now on your finger and likely to be picked up by the test. "If I just was eating an orange, I'll test high — I'm testing the orange, not my blood," explains Uelmen.

A study published in March 2011 in the journal Diabetes Carefound that blood from unwashed hands had a greater than 10 percent difference in blood sugar levels between the first drop and the second drop, and that error was amplified if participants' hands had recently touched fruit. The solution for better diabetes control: For the most accurate blood sugar testing, wash hands with soap and warm water and dry thoroughly right before testing.

Using the Same Finger All the Time

People choose to use the same finger and the same spot in part because everyone has a favorite, says Uelmen, and also because calluses build up and cut down on the discomfort. But varying your fingers is better.

The solution for better diabetes control: "The goal is to use a different finger each day or each time," she says. Switching fingers allows the pricked finger to heal and also helps to avoid pain caused by repeat jabs.

If your blood sugar readings are generally consistent, you can even try alternate site testing, such as using the palm of your hand, if you want to get away from your fingers periodically. But simply using different spots on the same finger can also prevent soreness.

Misusing Lancets and Test Strips

For the least pain and the most accurate results, you need the right blood sugar testing supplies: lancets, an accurate glucose meter, and manufacturer-recommended test strips. Skimping may not offer you the payoff you're hoping for; lancets start out very sharp but quickly get dull and will hurt if you try to reuse them, says Amori. Also, using expired or poorly stored test strips can result in inaccurate readings.

Solutions for better diabetes control: Use a fresh lancet, make sure test strips are stored in a closed container, and check the test strip expiration date before using.

Not Understanding Your Meter

Today's glucose meters are more sophisticated in their accuracy yet easier to use than ever before. Still, you need to check your meter's accuracy periodically — and you should follow the manufacturer's instructions for doing this correctly. You also need to know the fine points on how to use it and care for it, and what the error messages mean.

The solution for better diabetes control: If you're confused about the ins and outs of your meter, ask for help from your doctor, diabetes educator, or pharmacist.

Testing Too Soon After Eating

Knowing when to test and why that information is useful can help you better control your diabetes. "Often, people will test blood sugar half an hour or an hour after they eat," says Uelmen, but this is sooner than experts recommend.

Testing too soon after you've had a meal or a snack will give you results that are probably too high. The solution for better diabetes control: Test fasting blood sugar, and test every time before you eat. Wait two hours after eating to get the best reading.

Mindlessly Testing

If you test on a schedule without really knowing what those results are telling you, you could just be wasting test strips. You might have been given the recommendation to test once in the morning, before and after eating, and then before bed. These actually are good times to test, says Uelmen, as long as you're learning from the results and you understand why you're doing it. For instance, results taken before bed and in the morning are related, but you need to know why and how, so that you can make changes if necessary.

Solutions for better diabetes control: Check in with your diabetes educator or doctor to talk about your results and what they mean. Think of testing as a way to discover how your body responds to changes in medication, diet, activity, and sleep, rather than just a routine you're required to follow.