For 50 miles by a newbie, I'm going to guess you're riding >3 hours. North Alabama is similar to Cary (or at least Chapel Hill!), so I'm guessing your situation is similar to mine, although I've not been diagnosed as pre-diabetic.

Agree with Chaco on the electrolytes. Shoot for adding a Nuun to a water bottle when you refill after 2 hours. Gatorade, unfortunately, has turned into sugar water, so if you drink that stuff, add a salt pill. Alternately, see if your favorite convenience store has a V-8.

If you believe Gabe Mirkin (drmirkin.com), you'll exhaust your muscle and liver stores of sugar in two hours. That gives you liberty to eat carbs while you exercise, since the sugars will go straight to your muscles. I'd skip the Gatorade after the ride, and go for a peanut butter sandwich or something similar with a lower glycemic load, but with some protein. The goal at that point is to reload the muscles, without spiking your blood sugar.

Keep drinking! (water, that is.)