Type 2 Diabetes: Will Continuous Glucose Monitoring (CGM) Help?

Continuous glucose monitoring (CGM) has been found to help those with type 1 diabetes, especially those who use an insulin pump, manage their A1C and blood sugar fluctuations.

Now, researchers and doctors are branching out, wondering if CGM could help those with type 2 diabetes do the same.

The CGM system includes a tiny electrode, or glucose sensor, inserted under the skin to measure the glucose in tissue fluid. This electrode is connected to a transmitter that relays information to a monitoring and display device. If glucose drops too low or rises too high to alert  sounds.

So, could a CGM system help you?

Two experts weighed the pros and cons of CGM to manage type 2 diabetes at a recent symposium at the American Diabetes Association 77th Scientific Sessions in San Diego. While both experts see the potential for all patients with type 2, for argument's sake, they alternated taking pro and con sides.

Here, a recap of what is known about CGM for those with type 2 diabetes on multiple daily injections (MDI), basal insulin and non-insulin users.1

CGM for MDI Users

Multiple studies have found that CGM can reduce A1C and low blood sugar in those with type 1 diabetes, but do those findings translate to those with type 2? At least some research suggests they do, says Jeremy Pettus, MD, associate professor of medicine at the University of California San Diego.

Researchers assigned 158 people with type 2 diabetes to use CGM or self-monitoring of blood glucose (SMBG) and followed them for six months. At that point, those in the CGM group had an average A1C of 8%, compared to 7.7% in the SMBG group.

Critics often say older patients won't adapt to the CGM technology—which takes some learning—and that people without a higher education won't grasp it. That didn't bear out in this research, Dr. Pettus says.

During the study, no substantial changes were made in insulin doses or other medications, and he chalks up the power of CGM to people taking action when needed with all the feedback. "The A1C drop must be coming from lifestyle modification," he says.  That feedback, he believes, ''is empowering the patient."

More evidence is needed that it is the technology that is making the difference in the benefits that count, says William Polonsky, PhD, CDE, president and founder of the Behavioral Diabetes Institute and associate clinical professor of psychiatry, University of California San Diego. He points out that the study cited, called DiaMonD, excluded those with severe low blood sugar (hypoglycemia). Preventing it is one supposed benefit of using CGM.

Those in the study received intense support from their health care team, too, he says. In the ''real world,'' when patients don't always get intense support, he questions if the findings would be the same.1,2

CGM for Basal Insulin Users

Some research on using CGM for basal insulin users has found that it helps not only with monitoring blood sugar first thing in the morning but keeping tabs on what is happening overnight, which is important to know, Dr. Pettus says.

In one study, 65 people with type 2 were assigned to SMBG or CGM. Those on CGM reduced calorie intake, lost weight and doubled their exercise time. And the researchers found the AIC reductions in the CGM group persisted. "Can you imagine if that was a pill?" Dr. Pettus asks.3

In another study, researchers followed 26 people with type 2 diabetes given CGM, tracking them for six months. Their A1C declined, on average, from 8.9% to 7%. However, they also had great support from health care providers, Dr. Polonsky says. They could request a meeting with a diabetes educator (CDE) for more education about how to use CGM and how to make lifestyle changes. So, he asks, was it the technology or the human support? More evidence is needed in this group, he says.4

CGM for Non-Insulin Users

Poor blood sugar control is common among those with type 2 diabetes, Dr. Polonsky says. "One-third of patients have very poor control, with an A1C of over 9%," he says. Researchers and doctors know the reasons behind that lack of control, and you may know them, too.

Taking blood sugar measurements is time-consuming, bothersome and sometimes discouraging. As a result, some people just stop taking the measurements or take them much less often than they should.

With CGM, patients get constant feedback, Dr. Polonsky says. You eat a meal you know you should not have, and there are the consequences for you to see. The hope, he says, is that CGM use will help engage patients in their own care, help them feel more confident they can be safe, avoiding hypoglycemia, and improve their lifestyle habits based on the CGM feedback.

Even with the potential benefits, however, obstacles remain for using CGM by those with type 2 diabetes, Dr. Pettus says. One big barrier is coverage. It's often denied, and CGM is not cheap if you are paying out of pocket. 1

Prices vary, but the CGM receiver and transmitter can cost $1,000 or more and sensors can cost another $300 or more a month. 1

One alternative to CGM in this group, Dr. Pettus says, at least until insurance coverage improves, is to add another medication to achieve good blood glucose control.


While experts agree that more research is needed to figure out the best uses of CGM in those with type 2 diabetes, most also agree that the potential is great, says Joni Beck, PharmD, BC-ADM, CDE, clinical professor and clinical programs director of pediatric diabetes and endocrinology at the University of Oklahoma. She moderated the ADA session. 

As more research is done, she says, the potential may expand even more. "Although not clinically tested at this time, there is the potential to use CGM in those with pre-diabetes," she tells Endocrine Web. "This new technology offers significant insight into how we manage diabetes and the influence of lifestyle,  diet and exercise—on glucose control."1

Dr. Pettus is a consultant for Dexcom and Sensionics. Dr. Polonsky is a consultant for Dexcom and Abbott Diabetes Care. Dr. Beck has no disclosures.


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