Boosting NFC range for mobile device
Possible? Yes. Practical? Probably not.

This question might shed some light on yours. You'd need a pretty big antenna coil if you wanted to transmit a longer distance than one inch. Definitely not a size that could fit inside a smartphone comfortably. I think it'd be better to just use Bluetooth if possible.

NFC transmits through such small distances for mainly security purposes, so you'd want data like blood-sugar levels to be especially secure.