It sounds to me like your son has quite a few issues and needs help, but he would probably not recognise that.
May I ask a few questions: has the mother of the grandchild left your son?
Is the girlfriend a person you can talk to independently from your son?
Does the child's mother have access to her daughter at all?
Does your son have total custody of your grand daughter?
Can you mention all this to you Dr and ask if he can recommend how you may be able to report the emotional/controlling abuse of your son aver your grand daughter and everyone else.
Is your grand daughter suffering medically through incorrect care of her diabetes?
Is there some agency/department you can phone to voice your concerns about the treatment of your Grand daughter?
In the mean time, accept the conditions your son gives you and keep in touch with your grand daughter how ever you can until a solution can be found.
I hope some of this has made sense and is helpful to you.
Wishing you all the best and getting greater access to your grand daughter, maybe help for your son, and support for yourself as well with your own health concerns.
From Mrs. Dools