I'm type 1 diabetic. My nutrition training echoes what everyone has basically said here. That is, a good diet is: Lean protein (~1-2 oz per meal, when doing 3 meals a day), limited fats, veg carbs, fruit carbs, easy on the starchy carbs (grains essentially - like rice, flour-based products, oatmeal - and potatoes).
On the surface, that kinda sounds like the Paleo diet. But I don't know anything about it, and the "lowering your insulin to lose or maintain weight" sounds a little funky to me. Since I give myself insulin, I will tell you that a carb is a carb is a carb when it comes to insulin. 15 grams of carb, whether bread or veg, is going to take the same amount of insulin. The real difference is you'd have to eat three salads at least to take in the same amount as in 1 slice of bread.
I also find the glycemic index not worth it for similar reasons, which maybe the Paleo diet is supposed to leverage. There ARE some things like oatmeal or popcorn which take longer to metabolize, with a less sharp rise. But frankly they take sooo long, you might want to avoid them. The body wasn't meant to digest all day, to have insulin running through it 24x7. If we're talking about "lowering insulin" in that way, that might make sense - but what you have to do is the opposite of what people suggest.
If you are worried about bloodsugar spikes (which are really hard for the body to get under control), the thing you have to worry about is liquid sugar. I.e. soda AND fruit juice AND fruit.
My last thought is, they've done some studies about body types. Some people lose more weight cutting carbs and others cutting fats. Of course, a lot of times these are found together (like in a croissant). But personally, cutting fat is what does it for me.
