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Meta-Analysis Confirms Value of CGM in Type 1 Diabetes

EASD LISBON - Despite its limitations, continuous glucose monitoring appeared to improve glycemic control compared with self-monitoring in type 1 diabetes patients, researchers reported here.

In a meta-analysis, patients had significantly greater decreases in hemoglobin A1c (HbA1c) with continuous sensing rather than self-monitoring (P<0.001), Przemyslaw Rys, PhD, of HTA Consulting in Krakow, Poland, reported at the European Association for the Study of Diabetes meeting here.

Rys emphasized that the findings were only significant for real-time monitoring and not for retrospective monitoring.

There is ongoing debate about the role of continuous glucose monitoring in diabetes as the devices have a host of limitations, including questions about accuracy of subcutaneous readings.

Several studies comparing the newer devices with self-monitoring have been published, so Rys and colleagues conducted a systematic review and meta-analysis of 14 studies, totaling 1,268 patients through January 2010.

Overall, they found a significantly greater decrease in HbA1c for those using continuous monitoring compared with self-monitoring of blood glucose (mean difference -0.26%, P<0.0001).

"What is important to emphasize is that the advantage of continuous monitoring proved only for real-time devices, not for retrospective continuous monitoring," he said.

Rys added that his group didn't see any evidence of publication bias across studies.

When stratified by age, changes in HbA1c were significantly greater for both adults and pediatric patients on continuous monitoring compared with self-monitoring (mean difference -0.30% for adults and -0.25% for children, P<0.001).

A meta-analysis of four studies found that continuous monitoring patients were about twice as likely to reach their HbA1c targets as those on self-monitoring, with a number needed to treat of about eight patients (OR 2.14, 95% CI 1.41 to 3.26).

The researchers also saw a significant reduction in hypoglycemic events for those on continuous monitoring, a difference that, again, was only significant for real-time but not retrospective monitoring.

There were no differences between groups in terms of the percentage of patients who had at least one severe hypoglycemic episode, and the risk of ketoacidosis was comparable in both groups.

As well, safety analyses showed that continuous monitoring was well-tolerated. Reported adverse events included reactions at the sensor implantation site, such as tenderness and reddening. But no severe adverse events were observed.

Rys noted that data regarding time spent in hypoglycemia and hyperglycemia were incomplete and heterogeneous, so a meta-analysis wasn't possible.

Still, he concluded that continuous monitoring may contribute to improvement in glycemic control that manifests as significant drops in HbA1c and fewer hypoglycemic episodes.

The study was limited because all the trials included were of either low or medium quality, Rys said. Also, there were no data on long-term safety and efficacy.

The study was supported by Medtronic Poland.
Kristina Fiore
Staff Writer, MedPage Today, September 18th, 2011
Source: European Association for the Study of Diabetes (EASD)
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