Has he been seen by social services? You can self refer, you don’t need the GP to do it although I would have expected the hospital to refer. He sounds like he needs a full assessment of his needs with both the diabetes and the falls. He may also benefit from a referral to the falls clinic, there is usually a dedicated outpatients clinic for the elderly who have experienced several falls to help prevent future injury. It may also be worth seeing if you can get a referral to a geriatrician (the GP should be able to do that) who again is someone who can look at your dad’s condition as a whole human being not just treating each crisis.
I was thinking same kind of thing, they should be looking at your father as a whole, not as just a diabetic, they should be giving him an MOT after so many admissions.
It's difficult because they will look at the reason for admissions and patch that up and discharge him, especially if there are no other conditions on the medical records.
Get your dad to write a letter, or type it up and have your dad sign it, giving you and your siblings permission to speak with the doctors and nurses at his surgery about his health. Then you can speak on the phone with them or make appointments in the surgery to see them, booked under your fathers name - I do with this with my mum.
BEFORE THAT if you think it's not just diabetes, that your father might be developing dementia, do an online application for Power of Attorney, for finances and one for health and welfare, it's not cheap but you must do it NOW. You have an option to notify people on it, don't need to. It can take up to 6 months to process and the person granting power of attorney must be of sound mind ie able to grant that permission. If the GP or hospital diagnose dementia then it may or may not be too late depending on state of mind. Without this you cannot make any decisions on behalf of your father if he does develop into full blown dementia, all the decisions will be made by professionals, but with power of attorney you would have some say on things acting in the best interests of your father.
I can't really comment on the diabetes as I am a carer for my mum's type 2.
It's a learning curve, who, what, how to get results and what other help there may be. Your father has been having unsafe discharge from hospital. Social services don't like that and his GP won't either. You need to consult with SS for assessment and with GP for further diagnosis beyond diabetes in case of other things going on eg urine infection which can confuse, or whatever else in case there are other things going on and brace yourself for stark reality of ageing and deterioration if not just diabetes/medication related, not a nice thought at all and we always hope for the best for our parents.
Keep strong and stay determined.