Or if there is anything I can do?
Sorry, because this is long.
My Grandparents are in their very late 70's. They have always been very young for their age and very active/organised etc. About 18 months ago my Grandfather started to become occasionally confused/forgetful and also agoraphobic. (he has had a period of his life where he was agoraphobic before) A few months ago, after being investigated for dementia etc he was told that he had had a number of tiny strokes that had affected his memory/clarity of thinking.
My Grandfather has always been very on the ball in all areas really and organised everything, particularly their finances, meticulously. He was very good with doing things online, the internet etc and has always researched every single thing they have ever done or bought very thoroughly. Now he can barely get online and at times can't even have a conversation as he forgets what he was trying to say or gets too tired. He does also have some breathing porblems, which doesn't help. This is so sad, the one thing he always said he dreaded was his 'mind going'. 
My Grandmother insists she is fine. However, my sister and I have noticed she is also getting forgetful/absent minded. There's also the fact that she doesn't even know how to turn the computer on and has never done any of the organising of anything, my Grandfather has done it all.
They are both very proud and will not admit they need help, but both my sister and I feel they do. I live very far away and my sister lives where were grew up, but my Grandparents moved 'away' to be near my Grandmother's siblings etc once my sister and I grew up. My father is a waste of space and lives abroad anyway, so any relatives near my Grandparents are as elderly or older than them. My sister has suggested that perhaps my Grandparents move closer to them so her and her DH can help them out and also see more of them. They do not want to do this. My Grandmother insists they have lots of friends and family to help, but my sister and I have never met any of these friends and my Grandmother does sort of live in a sort of fantasy world and as she is friendly with people, for example neighbours and people at the gym, she feels these are her friends whereas my sister and i feel they are probably being polite and friendly, but aren't actual friends. Eg. they never go round for a coffee or go out together, just chat in the street, at the gym etc. It also seems like my Grandparents go out of their way to help their family members but not vice versa. They are very kind, giving people and my Grandmother in particular loves to help people.
My Grandparents are coming to stay for a few days next month. I am hoping I can chat to them then, but I'm not sure what to say. I supect they will just insist they do not need help and I don't really see what I can do?
I hope this makes sense, I really feel very upset about it all. I am sure my Grandmother would feel IABU to be worried, but am I?