Last week I learned of yet another company, Echo Therapuetics out of the Boston area, that is developing a transdermal continuous glucose monitoring system for people with diabetes. Naturally that means a non-invasive monitor that takes constant readings through your skin.
Been there. Heard that. Right?
Well, allow me to briefly introduce their work before we get into the discussion about whether skin-surface monitoring will ever succeed.
Echo's Symphony system is made up of four separate parts: the Preludeâ„¢ skin permeation system, transdermal sensor, wireless transmitter and wireless remote monitor.
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If I am reading this detailed analyst report correctly, here's how it all works:
1) The user employs the ultra-sensitive Prelude hand-held device to scan the skin and apply the transdermal glucose sensor.
The weird bit is that the Prelude actually removes the stratum corneum (the outermost layer of the epidermis) — painlessly, they claim — "which enhances the flow of interstitial fluids and molecules to the Symphony transdermal sensor."
The magic of the system is apparently in the Prelude's "proprietary feedback control mechanism, which consists of software, microprocessor controlled circuit and measuring electrodes."
Its function is to measure the real-time electrical conductivity under the skin, and automatically turn off the system when a certain skin depth is reached. That's the point at which the transdermal glucose sensor is adhered to you.
2) The sensor that's put in place consists of "an electrochemical glucose sensor, a hydrogel layer, a potentiostat and a short-range RF9 transmitter." It takes readings every 20 seconds, and a three-reading average is sent to the monitor every minute, which is what you'll view.
3) It sounds like there's no lengthy start-up period: "Once the sensor and the transmitter are adhered to the skin, the transmitter automatically starts to send data to the monitor, once every minute." However, the sensor can only be worn up to 24 hours (!)
4) The Symphony monitor will display the date, time of day, sensor current, blood glucose reading and rate of increase or decrease, amount of time the transmitter has been switched on, battery status and any alarm or error modes.
NOTE: Echo Therapeutics states that they're also developing data transmission such that any portable device can receive, decode and display the Symphony's data. (Now that would be cool.)
They are targeting mid-2010 to submit this system for FDA approval.
The company has already run three small pilot studies comparing its system with standard blood glucose meters and with hospital-grade blood gas and serum glucose meters. That all seemed to go well.
The company also plans to conduct one additional pilot study before starting its larger clinical trial for the FDA. The pre-trial will likely include about 350 patients in a hospital ICU setting, they state.
And I quote the report: "While we believe the trial should be successful, there are many factors that can cause it to fail..."
Interestingly, what comes next is a long discussion of the NICE-SUGAR clinical studies, and the resulting skittishness about tight blood sugar control, and a load of detail about the difference in types of FDA clearance that a company may be required to apply for.
Nothing about the GlucoWatch debacle, or the fact that no one has come up with a successful way to measure glucose without needles yet. And even if they did, I'm sure you'll agree that further compromises on accuracy are not in anyone's best interest. It better be at least as accurate as current fingerstick meters!
Still, the way I see it is: the odds are in our favor. The more organizations pushing towards needle-less measurement technology, and the more fuss the FDA makes over glucose meter accuracy, the more likely we are to see advances on both fronts.
I think it's all good as long as we are very, very patient (the hardest part about being a "patient," of course).