Continuous Glucose Sensor Can Help People With Diabetes Avoid Highs and Lows

---

Improvement in glycemic excursions with a transcutaneous, real-time continuous glucose sensor: a randomized controlled trial, by S. Garg and colleagues. Diabetes Care 29:44-50, 2006.

What is the problem and what is known about it so far?

Previous research has shown that intense insulin therapy delays and prevents heart and blood vessel problems in people with diabetes. By frequently checking their blood glucose levels, patients with diabetes are better able to monitor their A1C levels (a measure of long-term blood glucose levels) and to adjust their insulin doses to avoid extreme highs and lows in their glucose levels. Unfortunately, many patients who treat their diabetes with insulin don’t like to frequently check their blood glucose levels because doing so is uncomfortable and sometimes inconvenient.

Why did the researchers do this particular study?

Continuous glucose sensors have recently become available for patients with diabetes. These devices give patients the ability to view real-time blood glucose levels, review trends and fluctuations in their recent blood glucose levels, and receive alerts when their blood glucose level will become too high (hyperglycemia) or too low (hypoglycemia).

One type of continuous glucose sensor works by wirelessly transmitting glucose readings to a handheld receiver. A wire-like sensor that measures the glucose levels is inserted under the skin and is held in place by an adhesive. Once inserted, the patient wears the sensor for up to three days before replacing it. After three days, the patient simply removes the sensor from the skin and throws it away. A new sensor can then be used with the same receiver.

The researchers of this study wanted to see how accurate, safe, and effective this type of devise was for frequently checking blood glucose levels.

Who was studied?

A total of 91 patients who required insulin to treat their diabetes.

How was the study done?

The patients wore the continuous glucose sensor for three consecutive 3-day periods. All of the patients used two meters -- one for their normal fingerstick measurements and one for the continuous glucose sensor measurements -- but the patients were told to adjust their insulin doses according to their normal fingerstick measurements (not according to the values on the glucose sensor).

One group of patients (the display group) didn't see the glucose sensor measurements in the first period, but in the second and third periods, they were able to view real-time blood glucose levels, review trends and fluctuations in their recent blood glucose levels, and receive alerts when their blood glucose level would become too high or too low. The other group (the control group) wasn't able to see the glucose sensor readings during any of the three periods, and they didn't receive any alerts at all.

The researchers compared the different meter readings and monitored the blood glucose levels of the patients.

What did the researchers find?

About 95% of the glucose sensor readings were considered to be accurate when compared with the fingerstick meter readings.

The display group, or the patients who were able to use the glucose sensor in the second and third periods, spent 21% less time as hypoglycemic (blood glucose levels too low), 23% less time as hyperglycemic (blood glucose levels too high), and 26% more time in the target glucose range, as compared to patients in the control group.

What were the limitations of the study?

The improvements in glucose fluctuations could be because the patients were in frequent contact with the medical personnel who conducted this short 10-day study. Patients tend to monitor their glucose levels better when they know they’re being monitored.

What are the implications of the study?

Real-time monitoring of blood glucose levels, for periods up to 3 days, is safe, reliable, and effective for people who use insulin to treat their diabetes. Using this type of continuous monitoring system enables patients to avoid highs and lows in their blood glucose levels, which helps prevent diabetes complications.

FOR MORE INFORMATION

2006 Resource Guide, A Supplement to Diabetes Forecast

Fast Fact Series: Playing the Numbers