Most of my family is diabetic (type 2), including my parents. How do I avoid diabetes in future? I'm not fond of sweets but obese since childhood

diabetes. If your parents are diabetics, and you are obese, you have an extremely high likelihood of developing type 2 diabetes yourself. The only way to avoid it is to cure your obesity. Eat healthy food, cut out the carbs, sugars, soda, junk food, and do cardiovascular exercise 3-4 times a week. Fix your obesity and you will greatly reduce your risk of diabetes.
It's not sweets. It's total calories and weight. If you have a strong family history of t2 diabetes, your chances of developing diabetes yourself are 70-90% related to your weight. If you;re already overweight at age 17, you need to begin a life-long program of diet, exercise and weight loss or your chances of developing diabetes are very high. Talk w/your doctor and see a dietitian.