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Blood Glucose Monitoring

Blood glucose monitoring

Testing your blood sugar level is one of the best ways to understand your diabetes and how different foods, medications, and activities affect your diabetes. Keeping track of your blood glucose can help you and your doctor make a plan to manage this condition.

People use portable blood glucose meters, called glucometers, to check their blood sugar levels. These work by analyzing a small amount of blood, usually from a fingertip. The glucometer lightly pricks your skin to obtain the blood. Meters tell you your current blood sugar, but since blood sugar levels change, you need to test levels often and record them.

You can get blood glucose monitoring kits and supplies from:

  • your doctor’s office
  • a diabetes educator’s office
  • a pharmacy
  • online stores

You can discuss the price with your doctor or pharmacist. Glucose meters come with testing strips, small needles, or lancets, to prick your finger, and a device to hold the needle. The kit may include a logbook or you might be able to download the readings onto your computer.

Meters vary in cost and size. Some have added features to suit different needs and preferences. These may include:

  • audio capabilities for people with vision impairment
  • backlit screens to help you see them in low light
  • additional memory or data storage
  • preloaded test strips for people who have difficulty using their hands
  • USB ports to load information directly to a computer

What are the benefits of blood glucose monitoring?

Regular glucose monitoring is one of the ways people with diabetes can learn more about their condition. When it’s time to make important decisions about medication dosage, exercise, and diet, knowing your blood glucose levels will be a major help for you, your doctor, and the rest of your healthcare team. By checking your blood glucose levels routinely, you’ll also know when your blood sugar is too high or too low, both of which can cause symptoms and serious health problems.

Your doctor will calculate the target range for your blood glucose based on your age, your type of diabetes, your overall health, and other factors. It’s important to keep your glucose levels within your target range as best as you can. High blood sugar levels can lead to long-term complications if you don’t get treatment, such as:

  • heart disease
  • nerve damage
  • vision problems
  • poor blood flow
  • kidney disease

Low blood sugar levels can cause symptoms as well. The severity of these varies between different people. Some symptoms of low blood sugar include:

  • confusion
  • weakness
  • dizziness
  • jitteriness
  • sweating

Low blood sugar can also lead to serious, severe complications, such as seizures and coma.

What are the risks of blood glucose monitoring?

Risks from the blood glucose test are minimal and much lower than the risks of not monitoring your blood sugar levels.

If you share insulin needles and testing supplies with someone else, you’re at an increased risk of spreading certain illnesses, such as

  • HIV
  • AIDS
  • Hepatitis B
  • Hepatitis C

You should never share needles or finger-stick devices for any reason.

How to prepare for blood glucose monitoring

Before checking your blood glucose levels, make sure that you have:

  • a finger-stick device to prick your finger, such as a lancet
  • an alcohol swab to sterilize the puncture site
  • a blood glucose monitor
  • a bandage for if bleeding continues beyond a few drops

Also, depending on the type of test you’re taking, you may need to adjust your meal schedule or time it around your meal depending on your doctor’s instructions.

How is blood glucose monitoring performed?

Before you begin, wash your hands thoroughly to prevent infection at the finger-prick site. If you use alcohol wipes instead of washing, be sure to let the site dry completely before testing.

Next, put a testing strip into the meter. Prick your finger with the lancet to get a small drop of blood. Use the sides of the fingertips instead of the tip itself to decrease finger discomfort.

The blood goes on the test strip that you’ve inserted into the meter. Your monitor will analyze the blood and give you the blood glucose reading on its digital display usually within a minute.

Finger pricks rarely require a bandage, but you may want to use one if bleeding continues beyond a few drops. It’s important to follow all the instructions that came with your glucometer to ensure accurate results.

If you have type 1 diabetes, you may need to test your blood glucose three or more times per day. This includes before and after meals and exercise, and more often when you are sick.

If you have type 2 diabetes, your doctor will let you know when and how often to test your blood glucose.

Understanding results of blood glucose monitoring

The American Association of Clinical Endocrinologists and American College of Endocrinology recommends that you keep fasting and premeal glucose values at less than 110 milligrams per deciliter (mg/dL) and that you keep two-hour post-meal values under 140 mg/dL.

These are general guidelines. Ask your doctor about your target levels.

Regular blood glucose monitoring may feel like a hassle, but it’s an essential tool to help you take control of your diabetes. By identifying and recording changes in your blood sugar levels, you’ll have more information about how food, exercise, stress, and other factors affect your diabetes. 

Content licensed from:

Written by: Brian Krans
Medically reviewed on: May 25, 2016: University of Illinois-Chicago, College of Medicine

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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