In the Uptake (of nutrients) section, he talks about how plants absorb nutrients, including the following:
"There is some passive uptake of elements and the selectivity mechanisms are far from infallible, hence nutrient imbalances can arise, but these are routinely checked for by a conscientious grower and corrected as necessary."
This makes it sound like it doesn't matter whether someone has diabetes or not.
The pH of the soil has a huge impact (see the pretty picture below) on how grape vines absorb nutrients...and pH is mostly determined by the soil geology.
Clay particles (the smallest particles of soil, and do a majority of holding on to nutrients) are arranged differently (think snowflakes, sort of) depending on the soil geology. The different types of clay particles hold the various nutrients in differing amounts...affecting the grapes of course.
And, different types of clay particles cause the soil to swell (when wet) and contract (when dry) more or less, which could have an impact on grape vine performance.
Anyways, differing amounts of nutrients is certainly going to affect the grapes/wine and those are, to some degree anyways, affected by soil geology.
The bee in my bonnet about Minerality: he made an oblique reference to the "minerality doesn't exist because the roots don't take minerals up and deliver them to the grapes' argument. Minerality is just a descriptor for some wines. Many red wines have cherry flavors...but no one is arguing this because cherries are taken up from the soil to the grapes. Or earthy flavors in wine, etc. Comments like these by researchers/etc make me think they aren't paying attention, to the same thing I am anyways.