There's data to suggest that too much sugar can cause all kinds of problems to the brain, increasing oxidative stress is one of them.
Maybe the answer we're all looking for is to cut sugar from our diets.
If you cut back radically on carbohydrate consumption, see
https://en.wikipedia.org/wiki/Ketogenic_diet
you certainly will lower your blood sugar, your body will now use proteins and fat for energy as much as it can and produce both ketone bodies and glucose from those other macronutrients as well as stored fat and muscle tissues.
Table sugar and ‘high fructose corn syrup’ are roughly equivalent to 50% fructose and 50% glucose so far as your metabolism are concerned. Certainly fruit (rich in fructose and sometimes sugar alcohols) is good for you in moderation but probably not in excess. Your metabolism is certainly capable of converting fructose and some sugar alcohols into glucose. The story of what fructose does to you is much less studied than glucose. Certainly excessive amounts of sucrose and HFCS contribute empty calories that raise your blood sugar.