Monitor Your Diabetes
Check Your Blood Glucose Levels
Checking and recording your blood glucose levels can help you monitor and better manage your diabetes. If your blood has too much or too little glucose, you may need a change in your healthy eating plan, physical activity plan, or medicines.
A member of your health care team will show you how to check your blood glucose levels using a blood glucose meter. Your health care team can teach you how to
- prick your finger to get a drop of blood for testing
- use your meter to find out your blood glucose level from your drop of blood
More information is provided in the NIDDK health topic, Continuous Glucose Monitoring.
Your health insurance or Medicare may pay for the blood glucose meter and test strips you need.
Ask your doctor how often you should check your blood glucose levels. You may need to check before and after eating, before and after physical activity, before bed, and sometimes in the middle of the night. Make sure to keep a record of your blood glucose self-checks.
Target Range for Blood Glucose Levels
Most people with diabetes should try to keep their blood glucose levels as close as possible to the level of someone who doesn’t have diabetes. This normal target range is about 70 to 130. The closer to normal your blood glucose levels are, the lower your chance of developing serious health problems.
Ask your doctor what your target levels are and when you should check your blood glucose levels with a meter. Make copies of the chart in the section Your Diabetes Care Records (233 KB) to take with you when you visit your doctor.
Reaching your target range all of the time can be hard. Remember, the closer you get to your target range, the better you will feel.
The A1C Test
Another test for blood glucose, the A1C—also called the hemoglobin A1C test, HbA1C, or glycohemoglobin test—is a blood test that reflects the average level of glucose in your blood during the past 2 to 3 months.
You should have the A1C test at least twice a year. If your result is not on target, your doctor may have you take the test more often to see if your A1C improves.
For the test, your doctor will draw a sample of your blood during an office visit or send you to a lab to have your blood drawn. Your A1C test result is given as a percentage. Your A1C result plus the record of your blood glucose numbers show whether your blood glucose levels are under control.
- If your A1C result is too high, you may need to change your diabetes treatment plan. Your health care team can help you decide what part of your plan to change.
- If your A1C result is on target, then your diabetes treatment plan is working. The lower your A1C result, the lower your chance of having diabetes problems.
Talk with your doctor about what your A1C target should be. Your personal target may be above or below the target shown in the chart.
|Target for most people with diabetes||Below 7 Percent|
|Time to change my diabetes care plan||8 percent or above|
- how long you have had diabetes
- whether or not you have other health problems
Read more about A1C targets at the National Diabetes Education Program.
Tests for Ketones
You may need to check your blood or urine for ketones if you’re sick or if your blood glucose levels are above 240. Your body makes ketones when you burn fat instead of glucose for energy. If you have too many ketones, you are more likely to have a serious condition called ketoacidosis. If not treated, ketoacidosis can cause death.
Signs of ketoacidosis are
- fast breathing
- sweet-smelling breath
Ketoacidosis is more likely in people with type 1 diabetes.
Your doctor or diabetes educator will show you how to test for ketones.
Keep Daily Records
Make copies of the daily diabetes record at the end of this publication. Then, write down the results of your blood glucose checks each day. You may also want to record what you ate, how you felt, and whether you were physically active.
Bring your blood glucose records to all visits with your health care team. They can use your records to see whether you need changes in your diabetes medicines or in your healthy eating plan.
Learn about High and Low Blood Glucose Levels
Sometimes, no matter how hard you try to keep your blood glucose levels in your target range, they will be too high or too low. Blood glucose that’s too high or too low can make you feel sick. If you try to control your high or low blood glucose and can’t, you may become even sicker and need help. Talk with your doctor to learn how to handle these emergencies.
Learn about High Blood Glucose Levels
If your blood glucose levels stay above 180 for more than 1 to 2 hours, they may be too high. See the Daily Diabetes Record Page. High blood glucose, also called hyperglycemia, means you don’t have enough insulin in your body. High blood glucose can happen if you
- miss taking your diabetes medicines
- eat too much
- don’t get enough physical activity
- have an infection
- get sick
- are stressed
- take medicines that can cause high blood glucose
Be sure to tell your doctor about other medicines you take. When you’re sick, be sure to check your blood glucose levels and keep taking your diabetes medicines. Read more about how to take care of yourself when you’re sick in the section “Take Care of Your Diabetes during Special Times or Events.”
Signs that your blood glucose levels may be too high are the following:
- feeling thirsty
- feeling weak or tired
- urinating often
- having trouble paying attention
- blurry vision
- yeast infections
Very high blood glucose may also make you feel sick to your stomach.
If your blood glucose levels are high much of the time, or if you have symptoms of high blood glucose, call your doctor. You may need a change in your healthy eating plan, physical activity plan, or medicines.
Learn about Low Blood Glucose Levels
If your blood glucose levels drop below 70, you have low blood glucose, also called hypoglycemia. Low blood glucose can come on fast and can be caused by
- taking too much diabetes medicine
- missing or delaying a meal
- being more physically active than usual
- drinking alcoholic beverages
Sometimes, medicines you take for other health problems can cause your blood glucose levels to drop.
Signs your blood glucose levels may be too low are the following:
- dizziness or shakiness
- being pale
- sweating more
- anxiety or moodiness
- a fast heartbeat
If your blood glucose levels drop lower, you could have severe hypoglycemia, where you pass out or have a seizure. A seizure occurs when cells in the brain release a rush of energy that can cause changes in behavior or muscle contractions. Some seizures are life threatening.
If you have any of these symptoms, check your blood glucose levels. If your blood glucose levels are less than 70, have one of the following right away:
- three or four glucose tablets
- one serving of glucose gel—the amount equal to 15 grams of carbohydrates
- 1/2 cup, or 4 ounces, of fruit juice
- 1/2 cup, or 4 ounces, of a regular—nondiet—soft drink
- 1 cup, or 8 ounces, of milk
- five or six pieces of hard candy
- 1 tablespoon of sugar, syrup, or honey
Have one of these foods or drinks when your blood glucose levels are low.
After 15 minutes, check your blood glucose levels again. Repeat these steps until your blood glucose levels are 70 or above. If it will be at least 1 hour before your next meal, eat a snack.
If you take diabetes medicines that can cause low blood glucose, always carry food for emergencies. You should also wear a medical identification bracelet or necklace that says you have diabetes.
If you take insulin, keep a prescription glucagon kit at home and at other places where you often go. A glucagon kit has a vial of glucagon, a syringe, and a needle to inject the glucagon. Given as a shot, the glucagon quickly raises blood glucose. If you have severe hypoglycemia, you’ll need someone to help bring your blood glucose levels back to normal by giving you a glucagon shot. Show your family, friends, and coworkers how to give you a glucagon shot when you have severe hypoglycemia. Someone should call 911 for help if a glucagon kit is not available.
This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. The NIDDK translates and disseminates research findings through its clearinghouses and education programs to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.
The NIDDK would like to thank:
Michael L. Parchman, M.D., M.P.H., F.A.A.F.P., MacColl Center for Health Care Innovation, Group Health Research Institute; Marion J. Franz, M.S., R.D., L.D., C.D.E., Minneapolis, Minnesota
This information is not copyrighted. The NIDDK encourages people to share this content freely.