I had peripheral neuropathy (tingling in my hands and feet). It turned out to be a vitamin B deficiency. But while we were trying to figure out what was causing it, one of the options was that it was an early onset warning for diabetes. I asked the doctor what to do now so that I didn't get diabetes in five years, and he said, "lose X pounds". That set a target weight for me, and gave me a pretty strong incentive to try to hit it.

In actual fact, I tend to run about 2-3 pounds above my target, but I take stronger action above that.