My grand and greatgrandparents had diabetic retinopathy. how can i avoid it?

Luck/treatment: The inheritance of diabetes is not direct and hopefully you do not get it. If you are found to have this condition, then you need to every day pay attention to management of the blood sugar and the medication you will be placed upon. Retinopathy mostly occurs in those with poor control but a few get it anyway. It is treatable however. Good luck.

Don't get diabetes: If you already have diabetes, keep your A1c close to 6.5%, blood pressure less than 130/80, and get on an ace inhibitor or arb medication.