Here's my perspective, based on my recent experience.
Being in a situation where you find that you have diabetes, or that you are quite likely to develop it, is much, much worse than you can imagine unless you've gone through it. Consider never being able to have a piece of chocolate cake, pancakes, or a cookie. Not being able to eat the spaghetti that someone serves you at a dinner party. Imagine having to prick your fingers multiple times per day, or to have to inject yourself with insulin after every meal.
Trust me, it's different when it happens to you. This book can give you a feeling for it:
Amazon.com: The First Year: Type 2 Diabetes: An Essential Guide for the Newly Diagnosed (First Year, The) (9781569242650): Gretchen Becker, Allison B. Goldfine: Books
So, from that perspective, you want to do whatever it takes to avoid this. And avoiding it is easier if you start before your blood glucose levels get high enough to start wearing out your insulin-producing cells. There's a point of no return, and you want to take care of business before you reach that point.
It's true that if you don't have the diabetes genes, you're not going to get the disease no matter what you do. But if you do have those genes, the gun is loaded, and carbs and being overweight will pull the trigger.
I found out that my 66 year old sister has been pre-diabetic for a year (fasting glucose 103). Even if my test was an error, I'm not taking any chances. I'd rather be anorexic than diabetic.