I've had CFRD for 13 years now and a port for about 7 of those. Initially my CF doc said no way to a port because of the infection risk, but I was willing to take that risk considering how traumatic, inconvenient, and risky having PICC's can be. I had to get it replaced only due to a "mechanical" issue (catheter was being squeezed by my collar bone due to growth). Otherwise I've had no issues and I consider it the second best medical decision I've ever made (transplant being #1!!).
I think as long as you put in a concerted effort to keep your sugars in check you should be ok. . .if nothing else than for keeping infections under control.