Continuous glucose monitors (GCMs) aren't just tools of convenience for patients with Type 1 diabetes. They substantially improve blood sugar control, according to a new study presented this week during the annual meeting of the European Association for the Study of Diabetes (EASD; Rome).

Funded by the Juvenile Diabetes Research Foundation (JDRF; New York), the CGM study included 322 patients, ranging in age from 8 to 72, at 10 sites.

"The objective was to confirm that CGMs help patients to control their blood sugar. There are a lot of people who wanted to use CGMs, but some insurers still aren't paying and clinicians aren't prescribing them," Aaron Kowalski, program director for metabolic control at JDRF, told Medical Device Daily. "We're trying to provide rock-solid evidence for the potential benefits. This paper demonstrates that these conclusively benefit people with diabetes. We're hoping this will allow for better reimbursement and to help bring more clinicians on board."

CGMs provide both a real-time snapshot of the glucose levels of a person with diabetes and trend information. Much less invasive than fingersticks, a CGM uses a tiny electrode placed underneath the skin to measure glucose levels. The electrode is attached to a transmitter about the size of a key fob which is taped to the patient's abdomen. The transmitter then beams the information obtained from the sensor to a cell-phone sized receiver.

In the JDRF study, patients were assigned to either CGM use or a control group using standard blood sugar monitoring. They were followed for 26 weeks to assess effects on blood sugar control, principally assessed by measurement of the HbA1c level.

At enrollment into the study, patients had HbA1c levels of 7% to 10% (the goal for adults with Type 1 diabetes generally is a level below 7% and for children and adolescents below 7.5%-8%). Three age groups were analyzed separately: 8 to 14, 15 to 24, and 25 or older.

All of the participants benefitted, except for the teenagers, according to study results.

"This was really positive news in adults and the youngest kids, but it's not so clear in the middle group of teenagers," Kowalski said. "They're teenagers. They have a lot of other issues on their minds, dealing with college, peer pressures, etc. Then you put diabetes on top of that and it's challenging."

In addition to the challenges of being a teenager as a possible explanation, Kowalski also pointed out that the CGM devices would be easier to use – and more likely to be used — if made smaller so that they are more easily concealed.

Improvements in blood sugar control were greatest for CGM patients 25 years of age or older, whose HbA1c levels improved during the study by an average of 0.53% compared with control patients (p<0.001).

The improvement in HbA1c occurred without an increase in hypoglycemia (low blood sugar), which is the worry when attempting to tighten glucose control.

In children aged 8 to 14, the average decrease in HbA1c was not significantly different in the CGM and control groups; however, those in the CGM group were more likely to lower their HbA1c by at least 10% and achieve HbA1c levels below 7% compared with the control group.

More than one million patients in the U.S. have Type 1 diabetes, often referred to as juvenile diabetes. Of the 30,000 new patients diagnosed with Type 1 diabetes every year, almost half, or 13,000 patients, are children.

The vast majority of patients in the trial want to continue using the device, Kowalski said.

At a price of $500 to $1,000, they also have single-use components that last three to seven days and cost $30 to $50 each time.

Kowalski estimates roughly 60% of people are getting reimbursed. "Over the last three months, we've seen a major shift in payment. We've seen major plans make formal payment decisions, including Aetna, Humana and Wellpoint. We're seeing better access, but people still have to fight for reimbursement," Kowalski said.

"The key take-home message is that these technologies afford people with diabetes to do much, much better to reduce the risk of complications and lead an easier life," he said.

FDA-approved CGMs include:

The FreeStyle Navigator GCM, made by Abbott Laboratories (Abbott Park, Illinois). The FreeStyle was just approved earlier this year. It's designed to continuously measure glucose levels through a sensor placed in the back of the upper arm or abdomen. The sensor, worn for up to five days and then replaced, is placed just under the skin and attached to a plastic sensor mount with adhesive to adhere to the skin, like a patch (MDD, March 14, 2008).

• DexCom (San Diego) reported in January that it entered into a joint development agreement with Animas (West Chester, Pennsylvania) to integrate DexCom's CGM technology into Animas insulin pumps. The new product will be based on Animas' pump technology and DexCom's Seven, a seven-day CGM. It will enable the Animas pump to receive glucose readings and display this information on the pump's color screen. Users will have access to real-time glucose readings and trending in addition to receiving alerts for low and high glucose readings (MDD, Jan. 11, 2008).

• Medtronic (Minneapolis) was the first on the market in 2006 with a CGM product. The company received FDA approvals for the Guardian and the MiniMed Paradigm REAL-Time for use by adults (MDD, April 14, 2006). Then it received approval for use in children in 2007 (MDD, March 14, 2007).

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