Continuous Glucose Monitoring Works; Impractical for Toddlers

Neil Canavan

July 01, 2011

July 1, 2011 (San Diego, California) — A pilot study presented here at the American Diabetes Association (ADA) 71st Scientific Sessions suggests that the use of continuous glucose monitoring (CGM) devices in very young children with type 1 diabetes can be safe and effective.

However, study investigator Eva Tsalikian, MD, director, pediatric endocrinology and diabetes, University of Iowa Children's Hospital, Iowa City, stated that for widespread adoption of CGM in this population, next-generation CGM technology will be required.

Current models are too bulky and lack the required accuracy, Dr. Tsalikian asserted.

"No one has really looked at CMG use in very young children," she said, "So we performed this pilot study, a feasibility study, to see if these children can wear them, if they would they wear them, and for how long."

The investigators enrolled 23 children with type 1 diabetes and monitored them during a 6-month period. At enrolment, subjects were younger than 4 years (median age, 3.0 ± 0.8 years), had a median hemoglobin A1c (HbA1c) level of 8.0 ± 8% at baseline, and had a duration of type 1 diabetes mellitus of 0.7 years. Of these, 10 children were using an insulin pump and 13 used multiple daily injections to control blood glucose levels. All participants were provided a CGM device (FreeStyle Navigator [Abbott] or Paradigm [Medtronic]). Monitoring occurred at monthly intervals. At the end of the study, parents were asked to complete a treatment satisfaction questionnaire.

"In between these visits, the nurses and the coordinators of the study were calling the families," explained Dr. Tsalikian, "They instructed them on what to do with the numbers they see, with the arrows up and down and so forth, and we told them to keep the alarms on. They didn't exactly do what we told them, but that's no surprise." The use of CGM by children, and adolescents in particular, is often suboptimal at best, she acknowledged.

Dr. Tsalikian was generally encouraged by the results of the study. "By 6 months, about 50% of these children were using it more than 4 days a week. That compliance is exactly what we see in older children and adults. Teens do much worse."

Regarding blood sugar levels, the children were in the normal range roughly 45% of the time, with infrequent excursions in the lower ranges that define hypoglycemia. However, hyperglycemia (blood sugar levels in excess of 250 mg/dL) was observed nearly a third of the time.

"You say to yourself, [the parents] heard the alarms, why didn't they do something? Well, many of them discontinued the high alarm because it was too disruptive." This sounds irresponsible, but in defense of the parents, Dr. Tsalikian explained, a child's behavior with hypoglycemia is worryingly obvious, whereas in the hyperglycemic range, children behave normally.

"At least now these parents realize that their children are experiencing just as many hyperglycemic episodes, which they were missing, as hypoglycemic, which they successfully dealt with in this study."

Results for the questionnaire revealed ambivalence toward CGM use. When asked whether they thought the use of CGM was beneficial to their children, 89% of parents indicated that it was; when asked whether they would recommend CGM for other parents of children with type 1 diabetes, 90% indicated that they would not.

"Frankly, it's a hassle," admits Dr. Tsalikian. "They're already dealing with the pump, or daily injections, and to then add this, it's a lot to keep track of — perhaps too much." What she would like to see are CGMs that are smaller, with smaller needles and greater accuracy.

Dexcom: An Answer to CGM Accuracy?

Adjacent to Dr. Tsalikian's poster in the exhibit hall, and one that caught her eye, was a poster highlighting the use the prototype fourth-generation Dexcom CGM system.

This was a study of 70 children (average age, 12 years; mean duration of diabetes, 6.3 years; baseline HbA1c, 8.26 ± 1.49%). Of these participants, 59 children used an insulin pump, and 13 patients used multiple daily injections of insulin. Participants were instructed to wear the CGM device for 3 consecutive 7-day wear periods, with a new sensor provided for each period.

During the study there were no serious adverse events involving the prototype. There were no sensor fractures or infectious complications from needle insertion. Infrequent mild (12.0%) or moderate (1.2%) skin irritations at the sensor insertion and adhesive sites were observed.

Results for the HbA1c levels detected by the Dexcom CGM prototype were within 20% of the reference value 74.5% of the time; true alert rates were 88.3% at the high alert level of 200 mg/dL, and 67.0% at the low alert level of 80 mg/dL. The duration of diabetes, age, sex, and body mass index had no significant effect on CGM performance.

"Anecdotally, when you looked at these downloads as compared to previous Dexcom downloads," said lead investigator Bruce Buckingham, MD, from the Stanford University School of Medicine, Palo Alto, California, and Type 1 Diabetes TrialNet Co-Investigator, "[w]hen someone's [blood sugar level] is rising real rapidly, or falling, you would see these skips in the readout because there was a filter of about 3 mg/dL. With this device, you no longer see that; you really see a continuous curve. This is a significant improvement. I just wish it were available."

The Dexcom device is slated to be marketed in Europe and is not available in the United States at this time.

Dr. Tsalikian has disclosed no relevant financial relationships. Dr. Buckingham serves on advisory panels for Animas Corporation, Bayer Healthcare, Biodel Inc, GluMetrics, Inc, GlySens Inc, Medtronic, Novo Nordisk Inc, and Unomedical. He receives research from Abbott Diabetes and Dexcom.

American Diabetes Association (ADA) 71st Scientific Sessions: Abstracts 1218-P and 1219-P. Presented June 27, 2011.


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