Sensing the Big Picture With Continuous Glucose Monitoring

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Sensing the Big Picture with Continuous Glucose Monitoring

When you have diabetes, monitoring your blood glucose is a crucial part of your treatment plan. Knowing your blood glucose values can help you avoid short-term problems such as hyperglycemia (high blood glucose) and hypoglycemia (low blood glucose). Ongoing optimal blood glucose control can help you prevent or delay long-term diabetes complications such as diabetes-related eye disease, kidney disease, and nerve damage.

Typical blood glucose surveillance

Blood glucose monitors (often called meters) are such mainstays of diabetes care that most insurers, including Medicare, cover their cost. Certain conditions typically limit how often you can get a new meter and the amount of supplies that are covered on a daily basis. In some cases, this may restrict the frequency of your monitoring. To help make the most out of the supplies you have, work with your diabetes care team to determine the optimal times of day to check your blood glucose.

Continuous glucose monitoring

In less than two decades, the use of continuous glucose monitoring (CGM) for people with diabetes has gained popularity worldwide. This is largely due to improvement in the technology, the reliability of the information, and ease of use. A CGM system uses a tiny sensor less than one inch long inserted just below the skin. An electrode measures your blood glucose levels within the tissue fluid rather than directly from your blood. A transmitter attached to the sensor sends blood glucose information to a wireless monitor. Sensors typically require an initial blood glucose check with a meter for programming purposes. A receiver displays blood glucose results on a small screen in five-minute intervals. The unit also allows you to set and manage your sensor settings and alarms.

The sensors are used two ways. One is “real-time,” which means it is used on a day-to-day basis to monitor blood glucose levels. The other way is periodic use with a professional device from your diabetes care provider on a short-term basis (3- to 14-day sessions) to assist with troubleshooting related to blood glucose control. You can also consider this option to help you determine whether you would prefer to have your own CGM. Available software allows the sensor data to be downloaded to show your glucose patterns and trends.

Is CGM for me?

Experts currently recommend real-time CGM for adults with diabetes who are willing and able to use the device on a near-daily basis. If you have Type 1 diabetes — especially if you are using an insulin pump — the device can help you and your diabetes care team improve A1C levels that are outside your target goals. If your A1C is within the target range, CGM may help you identify and reduce hypoglycemia earlier. For example, CGM can alert you to variations in your blood glucose and identify frequent episodes of hypoglycemia that you may not be aware you are having. CGM may be beneficial if you have an active lifestyle or participate in athletic activities that require frequent monitoring to determine your blood glucose response. Diabetes care providers generally have less experience using CGM in those with Type 2 diabetes. This could be due to greater difficulty getting CGM covered by insurance for those with that condition. However, experts suggest that short-term, intermittent CGM may be helpful in people with Type 2 diabetes on basal (long-acting) insulin but not taking meal-time insulin who have A1C levels at 7% or greater. Particularly if you use insulin, CGM can help keep you safe by alerting you to extremes in blood glucose levels before they become dangerous.

If you are interested in CGM, ask your diabetes care provider for more information.

Here are some questions to ask:

• Does my insurance cover a CGM system?
• If not, does my insurance cover intermittent use of the device?
• If so, do I have a choice regarding the type of CGM system?
• What alarms and warnings are available?
• How would the alarms benefit me?

Your provider may refer you directly to your insurance company to determine your benefit for CGM. Be sure you ask the insurer for the criteria used to determine the need for a CGM system, which will likely include a prescription from your diabetes care provider. If your diabetes care provider has recommended CGM and you have difficulty determining your coverage for it, ask him or her to submit a prescription for the device you are most interested in to help you figure out requirements, cost, and long-term coverage.

Success with CGM

To be absolutely clear, having a device that continuously monitors blood glucose levels does not guarantee optimal control. Success with CGM directly correlates to the level of education, capability, and willingness to use the device. Adequate education and training on the device includes 1) understanding that it does not replace usual blood glucose monitoring with a meter, 2) factors that may influence your ability to be successful with CGM, and 3) the overall technology components associated with CGM use (see “Continuous Glucose Monitoring Education and Training“). While you may be able to cut back on the number of checks with your blood glucose meter, you will still need to calibrate the CGM and confirm extremely low or high blood glucose values using a check. Your diabetes care provider may request both for optimal blood glucose control. It is important to know that there is a lag time between a blood glucose fingerstick result from your meter compared to the sensor reading. Your diabetes care provider may recommend that you check your blood glucose using your meter to confirm hypoglycemia or hyperglycemia to determine proper treatment. The alarms that accompany CGM are an extra safety element; however, you and your diabetes care provider should discuss reasonable goals to avoid “alarm fatigue,” which can occur if you are overexposed to alarms (very frequent throughout the day) and become desensitized or less likely to respond to them. For example, your diabetes care provider may recommend that you start by focusing on alerts that help you recognize hypoglycemia and falling blood glucose levels first. Later, alerts that target high blood glucose numbers can be added.


Keep in mind that ongoing research to evaluate CGM is important to help us learn the benefits of using this technology in both Type 1 and Type 2 diabetes. If CGM is not an option that is currently recommended for you, make it a point to stay abreast of the technology and updates. If your diabetes care provider is a researcher or is willing to refer you to research using CGM, consider that option.

Your diabetes care team is interested in you and your diabetes health. Routine diabetes care and education is essential to help you stay on the path. If you are interested in CGM, ask your team questions about it and continue to ask for updates as technology improves. Above all, stay in control of your diabetes by knowing your blood glucose numbers and work with your team to keep them in the recommended range. Your health is absolutely worth it!

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