Obesity almost always leads to diabetes, but if you're not yet diabetic (and still in your thirties) there's still time to turn things around. Ask your doctor to screen you for the "early signs of diabetes". If you're significantly overweight, chances are good that you have the early signs.
I'm a big believer in being "scared straight" as a healthy motivation to lose weight. That's what got me to a drop 55 pounds -- a scary report from my doctor about my future. Diabetes is a terrible condition, but fortunately it's preventable. Schedule a screening today with your doctor if you've been unable to motivate yourself to lose weight any other way.