Patient education: Checking your blood sugar at home (The Basics)

Why do I need to check my blood sugar? — If you have diabetes and your blood sugar level gets too high or too low, it can cause problems. Many people with diabetes need to know how and when to check their blood sugar. "Glucose" is another word for sugar.

You might need to check your blood sugar to:

●Know how much insulin to give yourself (if you use insulin)

●Help you plan your meals, snacks, and exercise

●Know how your diabetes medicines are working

Your doctor or nurse will tell you how often and at what times of day to check your blood sugar. People who use 2 different types of insulin (background, also called "basal," and mealtime) need to check their blood sugar at least 4 times a day, including before each meal and at bedtime.

You will need to track your results over time. This will help keep your diabetes under control. It will also help your doctor figure out if you need to change your treatment plan.

How do I check my blood sugar? — There are 2 ways to check your sugar level. One involves using a "blood glucose meter" to test a drop of your blood. The other involves wearing a "continuous glucose monitoring" or "CGM" device that checks the level for you.

Your device will come with specific directions. Read these carefully to make sure that you know how to use it correctly. Below are the general steps involved.

To use a blood glucose meter:

●Wash your hands with soap and water, then dry them.

●Get your meter ready. Put a new test strip in.

●Choose the finger you will prick. Try not to use the same finger every time. You might also be able to prick other places, such as your forearm. Your doctor or nurse will tell you if you can do this.

●Use a fresh small needle or "lancet" to prick the side of your fingertip (picture 1). You will feel a sharp stick and a little discomfort.

●Get a drop of blood. You might have to squeeze your finger to get the drop.

●Touch the edge of the test strip to the drop of blood.

●The meter will show your blood sugar level. Write this down so you can share it with your doctor or nurse.

●Throw the needle away in a special container meant for this (picture 2). Do not throw used needles in the regular trash.

CGM devices check your sugar level automatically. They measure the sugar in the fluid under your skin, rather than in your blood. These are most often used by people who take multiple insulin doses each day or use an insulin pump.

To use a CGM device, you need a:

●Sensor – This goes under the skin of your belly or arm. The sensor is usually changed once every 7 to 14 days, depending on which device you have. One sensor can last up to 90 days.

●Transmitter – This goes on your skin, over the sensor. It is held in place with a sticky patch.

●Reader – This can be a small recording device or a smartphone app.

The sensor measures your sugar level. The transmitter sends the information to the recording device or your phone. You can attach the recording device to your clothing, carry it in a purse or bag, or place it near you (for example, on a bedside table while you sleep).

With some CGM devices, you can see your sugar levels in "real time" and share them with family members or your doctor or nurse (figure 1). With other devices, you periodically hold your smartphone over the sensor to see your sugar level (figure 2). (This is called "intermittently scanned.") Your doctor will talk to you about how to use your CGM and what to do with the information it provides.

Even if you use a CGM device, you might sometimes still need to check your blood sugar by pricking your skin.

What should my blood sugar level be? — Your doctor or nurse will talk to you about your goals, including what level is normal for you, what is too high, and what is too low. They will also tell you what to do if your blood sugar is too low or too high. In general:

●Low blood sugar is treated by eating a quick source of sugar. In an emergency, if you can't eat or drink, it can also be treated with a dose of a hormone called "glucagon."

●High blood sugar is treated with insulin or other medicines. Your doctor might tell you to test your urine for ketones if your blood sugar measurement is high. (Ketones are chemicals that can build up in the blood when sugar levels get too high.) Based on the results, they might make changes to your medicines, diet, or exercise plan.

When should I call the doctor? — Call if you have any questions about how or when to check your blood sugar, or if you are not sure what to do about the results.

You should also call if you have:

●Symptoms of low blood sugar – These include sweating, shaking, hunger, and feeling worried.

●Symptoms of high blood sugar – These include intense thirst, feeling very tired, urinating often, weight loss, and blurred vision.

More on this topic

Patient education: Type 1 diabetes (The Basics)
Patient education: Type 2 diabetes (The Basics)
Patient education: Using insulin (The Basics)
Patient education: Giving your child insulin (The Basics)
Patient education: Checking your child's blood sugar level (The Basics)
Patient education: Treatment for type 2 diabetes (The Basics)
Patient education: Low blood sugar in people with diabetes (The Basics)
Patient education: Managing diabetes in school (The Basics)
Patient education: Hemoglobin A1C tests (The Basics)
Patient education: How to dispose of needles and other sharps (The Basics)
Patient education: Keeping track of your blood sugar (The Basics)

Patient education: Type 1 diabetes: Overview (Beyond the Basics)
Patient education: Type 2 diabetes: Overview (Beyond the Basics)
Patient education: Glucose monitoring in diabetes (Beyond the Basics)
Patient education: Type 1 diabetes: Insulin treatment (Beyond the Basics)
Patient education: Type 2 diabetes: Insulin treatment (Beyond the Basics)