Self-testing is important, because it's "the only way to know for sure whether diabetes is under control," says Pilar Murphy, PharmD, an assistant professor at Samford University's McWhorter School of Pharmacy.
If you take insulin, your doctor might ask you to check your blood sugar, also called glucose, once or more daily. If you manage your condition with diet and exercise, you'll check your blood sugar regularly, but maybe not every day.
Your glucose meter measures the amount of sugar in a drop of your blood.
When you haven't eaten overnight, your blood sugar in the morning should be between 70 and 130. That's called fasting glucose. About an hour or two after the start of a meal, your blood sugar should be less than 180. That's called postprandial glucose.
These numbers show how food, exercise, stress, and sickness affect blood sugar. "It helps patients see, for example, if they eat a lot of bread, their sugar will go up," Murphy says.
What if your sugar is too low? If your blood sugar is below 70, you should eat or drink 15 to 20 grams of simple carbohydrates, then check your sugar again in 15 minutes. (You can get 15 to 20 grams of simple carbohydrates from 2 tablespoons of raisins or a tablespoon of honey.) Repeat these steps until your blood sugar returns to normal.
If your sugar tests high on occasion, drink water to avoid dehydration. And if it's over 240, check your urine or blood for ketones with test strips available at the drugstore. This chemical circulates in your blood and urine when your body begins to break down fat for energy instead of sugar. Call your doctor right away if you have moderate to high levels of ketones in the blood, because that can be poisonous.