New glucose monitors pump up sweet control

Better readings help diabetes treatment

By Gloria Gaspard

The saying "knowledge is power" is seldom truer than in the case of diabetics, who need constant blood sugar readings in order to receive the best treatment. Now, new devices — called continuous glucose monitors — aim to make diabetes easier to track. These monitors take a reading every five minutes, providing much more information about trends and patterns than can be gleaned from traditional, intermittent finger sticks. "These devices will really make a difference in patient control," says Dr Bernard Zinman, director of the diabetes clinic at Mount Sinai Hospital in Toronto.

The latest in a long line of attempts at developing the ideal continuous monitor combines a pager-like device with an insulin pump that can be programmed by the patient to deliver insulin at varying rates. Licensed in Canada several weeks before it was granted FDA approval on April 13, the device is already being used diagnostically by endocrinologists to help patients better understand how to manage their disease. "We use them in the same way a cardiologist would use a Holter monitor to look at cardiac rhythms," says Dr Hertzel Gerstein, an endocrinologist at Hamilton Health Sciences.

KNOWLEDGE IS BLISS
A sensor is inserted in the subcutaneous tissue of the abdomen that relays regular readings taken from interstitial fluid to a monitor that's worn on the belt. The device isn't fully automated yet — patients still have to read and interpret the result. But it does bring us one step closer to the coveted "closed loop system" where diabetics won't have to think about if, when and how much insulin they need. "We're putting people on it for three days, and analyzing the data," explains Dr Zinman. He says it's used primarily to help patients understand what happens when they eat Chinese food, or go for a run, for example.

By far the greatest advantage of these devices is the pure wealth of information they provide — patients can observe the direction, duration, frequency and possible causes of fluctuations in blood glucose levels. But it's going to take some time and lots of tests before patients will give up complete control. "The consequences of even a tiny error [in insulin administration] are huge," says Dr Gerstein. "Right now, no one would trust their insulin management to a machine, but that's what we're hoping for eventually."

STICKER SHOCK
At this stage, the devices still have to be calibrated several times a day with finger stick readings, so patients aren't free of painful pricking just yet. And though the accuracy of the devices — particularly in the hypoglycemic range — has been called into question, both Dr Zinman and Dr Gerstein agree that the real drawback is cost, not accuracy. Each sensor lasts three days and costs about $40 apiece, while the device itself can run up to a couple thousand dollars. "It's not practical for someone to wear all the time," says Dr Zinman. He adds that while the cost-benefit ratio is a concern, better glucose control would mean fewer complications and tremendous savings for our healthcare system. "It's remarkable that people with diabetes do as well as they do now with intermittent monitoring."