The Special Constabulary:
You have more chance of becoming a part time special constable (volunteer) than the regular police, but the entry requirements are still quite hard and there's still a lot of training involved, but it is somewhat easier and realistically you might stand a very slim chance. They're more likely to accept an autistic individual although don't get me wrong it will still be very difficult to get in and then they can probably work your hours around your benefit situation. Most special constables will go out under the wing of regular officers or they can be assigned to less risky tasks like policing low risk special events, although there are some more experienced special constables that work exactly like regular police and the public wouldn't even notice that they're a special constable. A special constable has exactly the same arrest rights as any other police officer in the UK. Some people become special constables first and later become fully paid regular officers after they've gained a lot of experience because this massively increases their chances.
Remember they have to be hard, even if they wanted to offer equal opportunities and be lenient, criminals on the street definitely wouldn't be lenient and will often seek out any weaknesses and use them against police officers, this is the harsh reality of the job.
I've read that having diabetes won't prevent you from being accepted on it's own as long as hypertension is properly controlled by meds, although you will still have to pass other fitness tests.
I notice there is a presentation event on Tuesday 22 May, 2018 at 6.30pm at South Yorkshire Police Sports and Social Club, Niagara Conference & Leisure Centre, Niagara Road, Sheffield, S6 1LU, please see the link below:
Applying to be a Special Constable - SYP
This isn't specifically South Yorkshire Police, but it should be relevant throughout the UK:
You still have to pass a similar fitness test to the regular police even as a special constable:
If you made the special constabulary I'd be extremely impressed, go ahead make my day. Best of luck!
PS: Even the application form is huge, or it certainly used to be.