Thanks for the info Part. I'm fond of medical information.

We've not had anyone with diabetes in our family so the chance of being prone to this disease genetically is really low. However my older brother who is over 40 years old was diagnosed with pre-diabetes a year ago. He LOVES eating anything sweet and he'd eat a lot of it. His work also was so stressful as he had to finish designing a significantly huge petrochemical refinery unit. He had not much of exercise either. This went on until the time he couldn't bear the pain in his wrist and shoulder. His doctor had him to do a full check up and blood test and there he found that his blood sugar was relevantly high.
Fortunately with doing some exercise, eating less sweet things and lowering his stress a little he took both FPG and OGTT and things had went back to normal.

Long story short, as Partagas mentioned; lack of exercise, stressful life and your eating habits as you get older can cause diabetes so watch out and do a regular check up and blood test.