I don't think anyone can truly answer that yet.

I just wanted to show you that the two systems are SEPARATE.

If you test as diabetic with a glucometer, that will not tell what is happening in the brain as well.

I have not seen work or papers yet on brain injury and type 3 diabetes (in the brain only ).

Anyone can develop regular type 2 diabetes anytime, and even when at a younger age now. Some teens who are very overweight or obese are developing it. So really, eating well and avoiding sugar and lots of starchy carbs may level blood sugars out so they do not go very low or very high. The Zone diet is one that does this. You can look it up on the net or read Dr. Sears' books.

Eating or drinking sugar sets up a cycle of rapid blood sugar spike followed within an hour of a rapid fall and low, which is perceived by the body as anxiety, sweating, shakiness and muscle twitches. By eating slow carbs, and protein in better ratios, these swings can be avoided, and you feel better.
Sugared drinks and juices are to be avoided. Candy, etc.
Slow carbs are beans, legumes, nuts, pasta, carrots, and some fruit with lots fiber...whole oranges, peaches, berries.