Hi Anta,
While the medical world says that the chances are more, it is not necessary that one has to get because one or both the parent has it or does not have it.
To the question how can I avoid/postpone - choose a diet that is very low in carb (you need to check with your doctor before embarking on this path). Do not plan to consume more than 40g of carb per day. And make sure you work out in a gym and keep yourself fit. The low carb will ensure that your body will produce less insulin and ensure that your pancreas will do its job for more years than eating more carbs and burning the beta cells of pancreas (that produces insulin).
Please read more on these things and consult your doctor before changing anything drastic. I am Type II diabetic (My mom has) and was dxed at the age 28 and I am on a Low Carb diet maintaining the Blook Glucose between 80 and 90 always.
Thanks
Venkat