My mother is diabetic and even I have high sugar levels. Will my son, who is a little plump, in the risk group for diabetes too?

Yes, there are strong chances that your son can have diabetes as diabetes is acquired genetically too. Please keep a check on his weight and inculcate habits of healthy lifestyle in him. Encourage him to play any sport. Stop giving him junk. Don't store junk food in the fridge. Its better to be aware from early on. http://www.diabetes.co.uk/diabetes-and-genetics.html