Sugar

So, she can't have sugar?

It is completely possible you believe this to be true. It stands to reason that, if having a high blood sugar is what hospitalized her in the first place, having sugar in your blood is bad and you want to avoid all possible means of introducing more sugar into Brooklyn's body. In fact, this is so widely considered the case that there is a host of "sugar-free" products, from chocolate to syrup, that claim to be healthy choices compared to their sugar-laden compatriots.

In fact, you can have a reaction to having not enough sugar in your blood. It is a different situation with different symptoms from high blood sugar levels, but this is indeed one of the ways you could kill Brooklyn. To avoid that, you should not avoid sugar. You should instead assist her in maintaining a healthy amount of sugar in her bloodstream. This is what her pancreas would be doing if it was not in the eternal slumber of several thousand suns.