Me, I'm pushing 40 and still fighting the last few stubborn inches of visceral fat. A mere quarter cup of fresh blueberries left my tummy bloated for a couple of days! I have yet to measure my blood glucose, but after that kind of reaction to even a low glycemic fruit I'm reluctant to test it again...
Considering the sheer scale of sugary things I ate for the first 38 years of my life -- boxes of Ho Ho's, multiple huge portions of ice cream, cake and brownies, you name it! -- I don't think it's unreasonable to assume I did significant damage to my metabolism even given the lack of obvious symptoms like obesity, diabetes, etc. It's both that and my extensive readings of different authors which convinced me to try a more radical carbohydrate restriction (radical in the proper sense, striking to the root of the problem). I'm still in the process of arranging my finances to have some actual medical tests run, and although I don't have a baseline for comparison, it should at least provide some more information to help me decide which way to go next. But the only thing I advocate for everyone in general is high fat, moderate protein, low carb -- anything more specific is up to you to work out for yourself!
Give me a friendly Christian any day over an asshole atheist.