With career restrictions, it's important to know that rules are different for being recruited with diabetes, sometimes different for types 1 and 2 / insulin controlled or no insulin required (and many other conditions), and remaining in service if diabetes develops while working.
Rules can and do change eg until a few years ago, no-one with diabetes could join any fire brigades, nor remain if they developed diabetes while serving, but now, those with excellent control and no complications can join / remain.