Since I dont give the "health Credits" I have no Idea why you need to be here. Ask who ever gives the "credits". As for being over weight only 12% of the over weight people develop diabetes, 6% or 9% (I dont remember which) non obese people develop diabetes.
To address your BMI, you may look at eating a low carb diet, avoiding sweets and sugars, and eating modest portions of food; such that you feel satisfied after eating, but not stuffed.
Daily exercise will also be very beneficial. Walking, biking, swimming for aerobic benefit, and then ideally some weight exercises for muscle strength.
If you are overweight, it would be recommended to have annual checking of blood sugars (fasting, and Hba1c - average 3 month blood sugars) to be sure you are not developing diabetes.
However, as mentioned by diabetes86, being overweight is not a guarantee that you will get diabetes. nor is being slim a guarantee that you won't.