ADA 2008: Human factors make or break continuous glucose monitoring

Real-time continuous glucose monitoring (CGM) can significantly improve glycemic control, but it will not help all patients. "Real-time CGM will add significantly to glucose management for some people, but not for all," said Irl Hirsch, MD, University of Washington, Seattle. "Human factors make all the difference between success and failure. Some patients will never figure it out. That's why real-time control is so challenging."

Those patients who are interested in the technology, motivated to change their behavior in order to manage their diabetes, and who are in an appropriate supportive environment can use real-time monitoring very effectively. Patients who are less interested, less motivated, and in a less-supportive environment will show little or no improvement.

One of the key factors to successful real-time monitoring is actually using the technology. "You have to look at the sensor in order for the sensor to [be effective]" Dr. Hirsch said.

Studies show that patients who use the sensor less than 60% of the time show no benefit from real-time monitoring. This is because they are not using the sensor consistently and are not using monitoring data to adjust their behavior in ways that can improve management.

A second key factor is using the sensor properly. Patients who fear hypoglycemia often use real-time monitoring to keep their glucose levels above the target zone in order to avoid hypoglycemic episodes. "Patients who are hypoglycemiaphobic can use the monitor very effectively," Dr. Hirsh said. "They just use it in the wrong way."

Patient environment crucial
The patient's environment is also a crucial factor in successful real-time monitoring. Patients who are devoted to an active social life with lots of parties, lots of snacking and lots of drinking are much less likely to successfully manage glucose levels than patients who are in a more stable and controlled environment.

The patient's success or failure in glucose management before moving to real-time monitoring is also predictive of success or failure. For example, patients with the worst A1c levels, 9.5 and above, may not be ideal candidates for real-time monitoring, Dr. Hirsch said. Such high A1c levels suggest that these individuals are not paying attention to their glucose levels or to their diabetes.

"If you have an A1c of 9.5 in 2008, you are doing something wrong," Dr. Hirsch said. "There is a good chance that you will never get control, even with real-time monitoring because glucose [management] is not a high priority in your life."