While a lot of comments revolve around the efficacy of accurately monitoring for T1/2 diabetes and the past noninvasive trials and tribulations thereof, consider that the market for such a product is very limited by Apple's measure (10's of millions for an addressable market, versus billions for phones/watches). It seems much more interesting if they were chasing a general metabolic health or pre-diabetic application where the annoyance and lethargy of the FDA/medical community can be skipped entirely.