Blood sugar can also be measured noninvasively through http://www.orsense.com/Glucose There no strong reason why their tool shouldn't be able to measure blood pressure, hemoglobin as well when they would have enough funding.

Vitamins are a bit more complicated as they appear in smaller quantities. I'm however not sure whether an implantable chip would do a better job at measuring vitamins. You can't easily refill chemicals in an implant. You can only transfer energy wirelessly (or you burn glucose). Energy allows you to run a centrifuge and a laser.

When you use implementable chips you won't be able to do fMRI on those patients anymore.