No worries; thought it was about time I gave back to the forum as have been reading it for long enough without contributing!
I've never asked about the traffic department, however I can't see that it would be a problem; I have heard of traffic officers with T2, but dont know any personally. And Diabetes certainly wouldn't stop you specialising in other departments, with financial crime being the obvious choice based on your current studies. I guess it's all down to the level of control you have. My control is pretty good at the moment, helped no doubt by the honeymoon period. If, however, I reach a point where I'm regularly stranded, unable to drive the car because my bloods have dropped unexpectedly before 5, then I would question my ability to perform this role and ask to be moved elsewhere. The last thing I want would be to put my colleagues and members of public in danger because I can't help due to hypoglycaemia.
Email the recruitment department but don't be put of if you get a negative response. I don't know what the current policy is but some forces may be more open that others. Be aware as well that some recruitment departments may manage a couple of different police forces, and not necessarily neighbouring ones, so be persistent!