Blood sugar levels give you information about how well your diabetes is under control. They also tell you how well your plan of diet, exercise, and medicine is working. Keeping your blood sugar levels near normal may reduce or prevent your risk for problems (complications).
Checking blood sugar levels regularly is very important in good diabetes management. Most methods of blood sugar monitoring need a blood sample. Blood sugar monitoring can be done at home with a variety of devices. They take the blood sample by pricking your skin with a small tool. A small device called a glucose meter or glucometer measures how much sugar is in the blood sample.
The drop of blood you get with a finger prick is often enough to use on a test strip. A finger prick can be done with a special needle (lancet) or with a spring-loaded device that quickly pricks the fingertip. You place the drop of blood on the test strip. Depending on the type of meter used, you may put the strip into the meter before or after you put the drop of blood on the test strip. The meter then reads the blood sugar level. Most meters are made to be used with the finger prick blood drop. But some meters can also be used with blood taken from the forearm or other site.
You can choose from many types of monitors. They range in price, ease of use, size, portability, and length of testing time. Each monitor needs its own type of test strip. Most blood sugar monitors give accurate results if used correctly. Most give results within seconds. Some blood sugar monitors can also "talk." They give instructions and results that you can hear if you have vision problems. Or if you have physical problems that make it hard for you to see the results. Some monitors can give oral instructions in Spanish and other languages.
Some monitoring devices can monitor blood sugar continuously for several days at a time. You may be able to set an alarm on the device so you can be warned if you blood sugar gets too low or too high.
You may have to check your blood sugar levels 4 or more times a day. Blood sugar levels can be affected by several things. These include:
Certain blood sugar monitors can store your results. You may be able to send this information to your healthcare provider's office electronically. You can also send this information to your home computer or mobile device. One advantage of this type of monitor is that it can show you your blood sugar levels as a graph. Mobile blood sugar monitoring apps are also available for tracking and sharing blood sugar results.
A finger prick can become painful and difficult if you need to do this on a regular basis. Several devices that don't need a blood sample are being developed. But most of these have not been approved by the FDA. Some of these devices use one of the following ways to measure blood sugar:
Infrared light to shine through a forearm or finger
Low-level electricity to draw blood up through the skin
Saliva or tears
To find out if a monitor is approved for use, call the FDA at SPAN: 888-INFO-FDA (800-463-6332). You can also check the FDA's website Blood Glucose Monitoring Devices section.
Continuous glucose monitoring (CGM) may be an option for checking blood sugar levels. It tracks your blood sugar level throughout the day and night. This can help you make better choices about food, physical activities, and taking medicines. It can also find trends and patterns that can help your healthcare provider better manage your diabetes. Ask your healthcare provider if CGM is right for you.
Several CGM devices are available. They are approved by the FDA with a prescription from a healthcare provider. It includes a sensor, transmitter, and a receiver or monitor. The sensor is a small device placed under the skin. It will measure your blood sugar several times a minute. A transmitter sends the information to a receiver. This may be a part of an insulin pump or a separate device.
Your blood sugar will still need to be checked a few times a day with a regular glucose meter to check for accuracy. The sensor under the skin needs to be replaced every 3 to 7 days.
Blood sugar levels over 180 mg/dl (mg/dl = milligrams of glucose per deciliter of blood) or under 70 mg/dl are considered unhealthy. High blood sugar levels (above 180 mg/dl) may be a sign of not enough insulin, caused by overeating, lack of exercise, or other factors. Low blood sugar levels (below 70 mg/dl) may be caused by taking too much insulin or other diabetes medicines, skipping or postponing a meal, over exercising, drinking excessive alcohol , or other factors.
> 180 mg/dl
Too high; considered unhealthy
80 - 130 mg/dl
Good range for most people
< 70 mg/dl
Too low; considered unhealthy
The American Diabetes Association (ADA) recommends a preprandial (before a meal) plasma glucose level of 80mg/dl to130 mg/dl. The ADA has set the postprandial (after a meal) plasma glucose level of less than 180 mg/dl.
These are the most common symptoms of hyperglycemia (high blood sugar). However, there may be no symptoms, and each person may experience symptoms differently. Symptoms may include:
Rapid, unexplained weight loss
These are the most common symptoms of hypoglycemia (low blood sugar). However, each person may experience symptoms differently. Symptoms may include:
Sudden moodiness or behavior changes
Rapid heart beat
Pale skin color
Sometimes, none of these warning symptoms appear before a person loses consciousness from low blood glucose. The loss of the ability to sense low blood sugar is called hypoglycemia unawareness.
Be sure to check with your insurance company to determine if blood glucose monitoring equipment and testing supplies are covered under your plan. If not, many suppliers offer rebates and/or discounted prices on trade-ins.
In addition, when selecting a glucose meter, the ADA reminds consumers to factor in the ongoing cost of test strips. Test strips can cost between 50 cents and one dollar per strip. Insurance providers vary on how many strips and how much of the test strip cost they will cover.