I'm not sure I understand the question, but I think the answer is no. There is no system of claiming benefits ad hoc for a day - even statutory sick pay doesn't kick in until you have been off sick for more than 4 days.
If you are very recently diagnosed it might be very up and down at the moment - if you are finding that's giving you bad days to the point where you can't work or look after yourself, speak to your DSN. Because it should be possible to manage diabetes to avoid that kind of impact if you have some help from your medical team on the right tools to use.