Monitoring Your Blood Sugar Level

If you have diabetes, it’s important to monitor your blood sugar at different times of the day and the year. There are 2 blood tests that can help you manage your diabetes—a daily test and a 3-month test. The 3-month test is called an A1C test. This test reflects your blood sugar (or blood glucose) control over the past 2-3 months. Testing your A1C level every 3 months is the best way for you and your doctor to understand how well your blood sugar levels are controlled. Your doctor will likely be the one who orders an A1C test. However, you can also purchase over-the-counter A1C testing kits that you can use at home.

Your A1C goal will be determined by your doctor. However, the goal is generally less than 7% or 8%, depending on your age.

The other test is a general blood glucose test. It is often referred to as self-monitoring of blood glucose. Using a blood glucose monitor to do regular testing through the day can help you improve control of your blood sugar levels. The results you get from glucose testing at home can help you make appropriate adjustments to your medicine, diet, and/or level of physical activity. If your blood sugar fluctuates, you should own a blood glucose monitor (also called a home blood sugar meter, a glucometer, or a glucose meter) and know how to use it. Your doctor may prescribe a blood glucose monitor.

The U.S. Food and Drug Administration (FDA) has approved meters that work without pricking your finger. But these meters cannot replace regular glucose meters. They are used to get additional readings between regular testing.

Path to improved health

What supplies do I need?

You will need a glucose meter, alcohol pads, sterile finger lancets (small needles), and sterile test strips. Check with your health insurance plan to see if they will pay for these supplies.

How do I pick a glucose meter?

Your doctor will make a recommendation. Check with your health insurance plan to see if it will pay for your glucose meter. If so, your plan may only pay for a certain meter.

Shop around and compare costs. Consider what features are important to you. For example, some meters are made for people who have poor eyesight. If you want to pay a little more money, you can get a meter that stores the results in its memory. This allows you to compare results from several days at one time. Other meters can be hooked up to your computer to analyze your results.

How do I measure my blood sugar level?

Follow your doctor’s advice and the instructions that come with the glucose meter. Different meters work differently, so be sure to check with your doctor for advice specifically for you. In general, you will follow the steps below:

  • Wash your hands and dry them well before doing the test.
  • Use an alcohol pad to clean the area that you’re going to prick. For most glucose meters, you will prick your fingertip. However, with some meters, you can also use your forearm, thigh, or the fleshy part of your hand. Ask your doctor what area you should use with your meter.
  • Prick yourself with a sterile lancet to get a drop of blood. (If you prick your fingertip, it may be easier and less painful to prick it on one side, not on the pad.)
  • Place the drop of blood on the test strip.
  • Follow the instructions for inserting the test strip into your glucose meter.
  • The meter will give you a number for your blood sugar level.

If you have severe diabetes, continuous blood sugar monitoring may be a viable option. These systems use a sensor placed beneath the skin that measures blood sugar constantly. Some insurance programs are beginning to cover these monitors.

What if I can’t get a drop of blood?

If you want to get blood from your fingertip, try washing your hands in hot water to get the blood flowing. Then dangle your hand below your heart for a minute. Prick your finger quickly and then put your hand back down below your heart. You might also try slowly squeezing the finger from the base to the tip.

How often should I test my blood sugar level?

Your family doctor will recommend how often you should test. Testing times are based on the kind of medicine you take and on how well your blood sugar levels are controlled. You’ll probably need to check your blood sugar more often at first. You’ll also check it more often when you feel sick or stressed, when you change your medicine, or if you’re pregnant.

What do I do with the results?

Write down the results in a record book. You can use a small notebook or ask your doctor for a blood testing record book. You may also want to keep track of what you have eaten, when you took medicine or insulin, and how active you have been during the day. This will help you see how these things affect your blood sugar. Talk with your doctor about what is a good range for your blood sugar level and what to do if your blood sugar is not within that range.

What time of day should I test?

Recommendations for the best time of day to test your blood sugar depend on your medicine, mealtimes, and blood sugar control. Your doctor may provide a chart that outlines when to check your blood sugar and what level you should target. Your doctor may also suggest different goals, depending on your situation.

The chart may look something like this:

Time to Test Fasting, Before Breakfast 1-2 Hours After Breakfast Before Lunch 1-2 Hours After Lunch Before Dinner 1-2 Hours After Dinner Bedtime 3 a.m.
Target Goal Ranges* 80-120 < 180 80-120 < 180 80-120 < 180 100-140 70-110
Doctor’s Recommendation
* Blood glucose values are measured from blood samples obtained from the finger or other sites, as read on your blood glucose monitor. The target goals are based on recommendations from a panel of medical experts. Talk to your doctor about what changes to make if your blood sugar levels are not within the range.

What do my blood sugar levels tell me?

Time of Test Can Be Used to …
Fasting blood sugar (FBG) nighttime (3-4 a.m.) Adjust medicine or long-acting insulin
Before a meal Modify meal or medicine
1-2 hours after a meal Learn how food affects sugar values (often the highest blood sugars of the day*)
At bedtime Adjust diet or medicine (last chance for the next 8 hours)

*Depends on the size of the meal and the amount of insulin in your medicine

Check your blood sugar if:

  • You have symptoms of low blood sugar (hypoglycemia). This includes dizziness, shaking, sweating, chills, and confusion.
  • You have symptoms of high blood sugar (hyperglycemia), which include sleepiness, blurry vision, frequent urination, and excessive thirst.
  • You need to learn how meals, physical activity, and medicine affect your blood sugar level.
  • You have a job in which poor blood sugar control could cause safety problems.
  • You need help deciding if it is safe to drive or perform other tasks that require concentration if you are taking insulin or have had hypoglycemia in the past.

When should I check my blood sugar more frequently?

  • If your diabetes medicine changes.
  • If you begin taking other kinds of medicines.
  • If you change your diet.
  • If your exercise routine or activity level changes.
  • If your level of stress increases.
  • If you are sick. When you are sick, even without eating, your sugar levels may run high, so testing is important.

Follow your doctor’s testing recommendations during this time. Continue testing more often until you have maintained your blood sugar goal values for at least 1 week. Or continue testing until your doctor advises you that more frequent testing is no longer necessary.

Tips on blood sugar testing:

  • Pay attention to expiration dates for test strips.
  • Use a big enough drop of blood.
  • Be sure your meter is set correctly.
  • Keep your meter clean.
  • Check the batteries of your meter.
  • Follow the instructions for the test carefully.
  • Write down the results and show them to your doctor.

Things to consider

Managing your blood sugar level is critical to your overall health. Often the focus is on keeping blood sugar levels low. But if they are too low, it can put you at risk, too.

Hypoglycemia is the name for a condition in which the level of sugar in your blood is too low. Your blood sugar level can get too low if you exercise more than usual or if you don’t eat enough. It also can get too low if you don’t eat on time or if you take too much insulin. Signs of hypoglycemia include:

  • Feeling very tired.
  • Yawning frequently.
  • Being unable to speak or think clearly.
  • Losing muscle coordination.
  • Sweating.
  • Twitching.
  • Having a seizure.
  • Suddenly feeling like you’re going to pass out.
  • Becoming very pale.
  • Losing consciousness.

How can I deal with an insulin reaction?

People who have diabetes should carry at least 15 grams of a fast-acting carbohydrate with them at all times in case of hypoglycemia or an insulin reaction. The following are examples of quick sources of energy that can relieve the symptoms of an insulin reaction:

  • Regular soda (not diet): ½ to ¾ cup
  • Fruit juice: ½ cup
  • Dried fruit: 2 tablespoons of raisins
  • Milk: 1 cup
  • Candy: 5 Lifesavers
  • Glucose tablets: 3 tablets (5 grams each)

If you don’t feel better 15 minutes after having a fast-acting carbohydrate, or if monitoring shows that your blood sugar level is still too low, have another 15 grams of a fast-acting carbohydrate.

Teach your friends, work colleagues, and family members how to treat hypoglycemia, because sometimes you may need their help. Also, keep a supply of glucagon on hand. Glucagon comes in a kit with a powder and a liquid that you must mix together and then inject. It will raise your blood sugar level. If you are unconscious, or you can’t eat or drink, another person can give you a shot of glucagon. Talk to your doctor to learn when and how to use glucagon.

Questions to ask your doctor

  • How often should I monitor my blood sugar level?
  • What type of device should I use to check my blood sugar level?
  • Do I need to take medicine to lower my blood sugar?
  • Can you show me how to use a glucose meter?
  • Do I need to track my daily results?


National Institutes of Health, MedlinePlus: Monitoring Blood Glucose

National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases: Managing Diabetes