I really hate to tell you this, but your father is not sliding towards type 2, he is already there. If his blood sugars are between 120 and 170, they are not normal. But you should take him to the doctor and have his blood work run to be sure. As far as what to tell a family member I can tell you what i said to my two daughters. I have two type 1 kids and am diabetic myself. After i was diagnosed, I talked to my three remaing daughters and told them about the danger for them. I consider two of them to be the most likely to become diabetic, We all changed our diets and our activities One of my daughters is a litle overweight and the other is very thin, but the thin one has a lot of problems due to being wheat and gluten and fructose intolerant The thrid daughter changed her diet and activites as well just in case. If prevention can work for us, we are doing everything to maintain a healthy lifestyle We have a lot of diabetes in our family. both type 1’s and type 2’s and i am the only type 1.5 so far. We get our vitamins, exercise, sleep and good healthy diets and good healthy habits for the most part. (one of the girls smokes) Other than that, I don’t know what else to do to try to prevent diabetes.
I wish you well.