Glucose Monitoring Devices

What is blood glucose monitoring?

Blood glucose levels (also called blood sugar levels) reflect how well diabetes is being controlled and how well the plan of care (diet, exercise, and medicine) is working. If the blood sugar levels are consistently under control (with levels near normal), diabetes complications may be reduced or even prevented.

How can blood sugar levels be checked?Man checking blood glucose

Checking blood glucose levels regularly is very important in proper diabetes management. Current methods of blood sugar monitoring require a blood sample. Blood sugar monitoring can be done at home with a variety of invasive devices to obtain the blood sample (invasive means the penetration of body tissue with a medical instrument).

Usually a drop of blood obtained through a finger prick is enough to use on a test strip that is then measured in a monitor. A finger prick can be done with a small lancet (special needle) or with a spring-loaded lancet device that punctures the fingertip quickly. The strip goes into the meter first, then a drop of blood is placed on the tip of the strip (also called a glucose meter or glucometer) that reads the blood sugar level.

There are many types of monitors on the market today. They range in price, ease of use, size, portability, and length of testing time. Each monitor needs its own type of testing strip. Most blood glucose monitors have been found to be accurate and reliable if correctly used, and most monitors give results within seconds. Some glucose monitors can also give verbal testing instructions and verbal test results for people who are visually or physically impaired. There are also glucose monitors available that provide verbal instructions in Spanish and other languages.

New monitoring systems are becoming available that can monitor blood sugar continuously for several days at a time. Users can set alarms so they can be warned if their sugars get too low or too high. 

People with diabetes may have to check their blood sugar levels up to 4 or more times a day. Blood sugar levels can be affected by several factors, including the following:

  • Diet

  • Diabetes medicine

  • Exercise

  • Stress

  • Illness

Certain blood glucose monitors are equipped with data-management systems. This means your blood glucose measurement is automatically stored each time. Some healthcare providers' offices have computer systems compatible with these data-management systems, which allows the blood sugar level recordings, and other information, to be transferred electronically. This can be done at your home computer as well. One advantage of a data-management system is the ability to plot a graph on the computer depicting patterns of blood sugar levels.

What are noninvasive blood glucose monitors?

A finger prick can become painful and difficult for a person with diabetes to do on a regular basis. Several noninvasive devices (that do not need an actual blood sample) are currently being researched to give people with diabetes an alternative. However, most noninvasive blood glucose monitoring devices have not yet been approved by the FDA. Some noninvasive devices currently under investigation include:

  • The use of infrared light to shine through the forearm or finger

  • The use of low-level electrical currents to draw blood up through the skin

  • The use of saliva or tears to measure glucose levels

To make sure that monitors are approved for use, the National Institute of Diabetes and Digestive and Kidney Diseases suggests that consumers call the FDA at 888-INFO-FDA (463-6332). You can also check the FDA's website Blood Glucose Monitoring Devices section.

What are healthy blood sugar level ranges?

Blood sugar levels over 200 mg/dl (mg/dl = milligrams of glucose per deciliter of blood) or under 70 mg/dl are considered unhealthy. High blood sugar levels (above 200 mg/dl) may be a sign of inadequate levels of 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, overexercising, excessive alcohol consumption, or other factors.

> 200 mg/dl

Too high; considered unhealthy

70 - 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 70 mg/dl to130 mg/dl. The ADA has set the postprandial (after a meal) plasma glucose level of less than 180 mg/dl.

The following are the most common symptoms of hyperglycemia (high blood sugar). However, there may be no symptoms, and each individual may experience symptoms differently. Symptoms may include:

  • Rapid, unexplained weight loss

  • Feeling sick

  • Intense thirst

  • Increased urination

  • Vomiting

  • Fatigue

  • Blurred vision

  • Fainting

The following are the most common symptoms of hypoglycemia (low blood sugar). However, each individual may experience symptoms differently. Symptoms may include:

  • Hunger

  • Fatigue

  • Shakiness

  • Headaches

  • Confusion

  • Dizziness

  • Sudden moodiness or behavior changes

  • Sweating

  • 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. 

Insurance and blood glucose monitoring

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.