It is highly unlikely that either Healthbook or the iWatch will be able to do even a fraction of these tasks, especially if Healthbook, like Passbook, is mainly a centralized location for easily accessing a specific type of information. And many of the "vital signs" Gurman names are cumbersome if not invasive.
Home blood pressure monitors, for example, require a wrap-around cuff of some kind. Here is Walmart's selection of home kits. One can make a reasonable argument that the iWatch band could also function as a monitor cuff, but that moves Apple more into the medical device manufacturing space than, frankly, seems advisable.
Monitoring glucose levels is a fancy way of saying "blood test." Current products all include some kind of "lancet" which is a fancy way of saying "very sharp, skin puncturing device to make you bleed." Typically the blood is then smeared on a test strip which turns one of several colors. The image of a continually stabbing iWatch probably won't feature in Apple's ad campaign.
(Google's recent announcement of its science project to create a contact lens that can measure glucose levels via tears which is not a new idea - generated lots of worshipful blog posts but also plenty of skepticism.)
Finally, and this is our favorite, "hydration levels." According to the National Academy of Sports Medicine, in post titled "Monitoring Hydration Levels," "Body weight and urine specific gravity (USG) are two common methods by which euhydration (maintaining normal total body water content) can be monitored." TopEndSports.com details the urine specific gravity method, step one of which is "Collecting the urine." Instantly, unbidden images come to mind of how one would use one's iWatch to do that.
To bolster his story, Gurman refers to a patent awarded to Apple for what he calls "technology for smartphones to track blood pressure." But if you search the patent's text, via Google Patent, the word "pressure" doesn't appear. Instead the patent is clearly identified as being for a "Seamlessly embedded heart rate monitor," a quite different purpose.
Gurman also links to a recent "New York Times" story about a December 2013 meeting between a group of Apple executives and the Federal Drug Administration (FDA). According to the Times: "Among the participants from Apple were Jeff Williams, senior vice president of operations; Bud Tribble, vice president of software technology at Apple; Michael O'Reilly, who joined Apple last year; and an employee from Apple's government affairs department. On the F.D.A. side of the table were Jeff Shuren, the director of the agency's Center for Devices and Radiological Health, and Bakul Patel, who drafted the F.D.A.'s mobile medical app guidance and is a staunch advocate for patient safety when it comes to apps and medical gadgets."
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