I am also Asian and surprised to find out that our ethnicity is highly prone to diabetes. It is all the rice we consume. Also, we tend to have higher blood pressure problems due to the soy sauce and all the pickled foods we love to eat. Tell your parents that this is a serious condition and that they can postpone or even avoid full blown diabetes only if they are willing to make lifestyle changes.
I didn't take my original diagnosis at age 47 very seriously when I was told I was pre-diabetic. I worked on it for awhile and then went right back to my old habits. Well, guess what? At age 60, I am now in full blown Type II diabetes and working really hard at trying to control my blood sugars and realizing how dumb I was not to stick with it earlier. Now I just pray it is not too late and have educated myself as to what I need to do. I exercise every day by walking 4-5 miles on a treadmill and watch everything I put into my mouth by counting carbs. Rice is out of my diet because I have noticed it really shoots up my blood sugar! But your parents could be different; they need to monitor their blood levels and get out there and walk! I wish you luck with them. I know how hard it is to get parents to listen. My mom had high blood pressure and just blew it off and refused to quit eating so much salt and to take her medicines. She ended up with mini-strokes that led to Alzheimer's and died at the age of 65. Very sad and I wish I could have her back. Keep after your parents. They're the only ones you will ever have.
Exercise is one factor in helping to lower blood sugars. In order to control and manage diabetes lifestyle changes must be made and followed; eating a proper diabetic nutrition/diet, maintaining normal body weight, daily 30-60 minutes of exercise, and having a normal lipid panel. Above all, follow doctor's instructions.
Use Google search for complications of type 2 diabetes. Show them to your parents. Although long-term complications of diabetes develop gradually, they can eventually be disabling or even life-threatening. Some of the complications are cardio issues [strokes & heart attacks], kidney failure, nerve damage leading to amputation, eye problems leading to blindness, skin problems, infections, and studies are showing Alzheimer's disease. They need to understand that ignoring their prediabetes will not prevent it from progressing to full blown diabetes. They need to understand these side effects WILL occur. They need to understand medicine/drugs does not cure diabetes, that lifestyle changes must be made if they wish to live a normal pain free life. Good luck -