Not all GPs have the training to give steroid injections into shoulders, so an untrained GP must refuse, but could refer to a colleague. However, views about when to use this treatment may have changed in 20 years.
I'm currently suffering a frozen shoulder, have consulted physio to get exercises to maintain the movement I have. GP declined steroid injection, although he can do it, as he reckoned the possible benefit wasn't enough to outweigh the risks, especially as my range of movement isn't too limited and I can deal with pain by taking ibuprofen. He also advised againsy hyodilatation, as mentioned by physio, for the same reason.
Although I've only had type 1 diabetes for 20 years, I'm not sure why you need regular mealtimes - basal bolus regime means I can eat any time of the day or night, and often work nights and very irregular hours, marshalling on mountain races etc.