Hiya!
Well, if you are not capable of carrying out your duties due to illl health, your employer is within their rights to dismiss you on grounds of ill health as you are not able to perform the duties you are contracted to perform. However, this has absolutely nothing to do with redundancy and must be handled completely separately.
Your employer must not use your diabetes against you when it comes to making redundancies - that would be disability discrimination. If they have used a points system to decide who gets made redundant, they must ensure that you were not disadvantaged in that system because of your disability. So, for example, if they are giving points for attendance, they must disregard absences due to disability and award your points on th,e basis of other absences. Therefore, if you haven't had the training in two machines because you were absent due to your disability, I think they have to disregard that. It's a tricky one, but they are certainly very close to discrimination.
If I were you, I'd ring Diabetes UK advocacy service. They will be able to give you the full facts and help you find out whether you have a case.
Good luck
Smidge