Depends on how "specialist" they are. I've had diabetes for 20 years. Used to be the GP who'd do the twice yearly reviews, who'd discuss the blood test results, "tweak" other medication such as blood pressure pills, give some pretty excellent dietary advice based on what I told him about what I ate, what exercise I did, etc. It was 15 minutes well spent!
Then around a decade ago, those reviews were taken over by the "diabetic" nurse who was OK, but couldn't "tweak" the prescriptions for other things, showed no real interest in my diet/exercise, and basically just increased the medication every couple of years when the HBA1C levels rose.
The last 2/3/4 years, it's been a different "diabetic nurse" each time, who've really not had a clue and showed no interest at all. Yes, they briefly check my feet (which I can do myself), but there's no conversation/advice at all. They spent the entire appointment filling in the questionnaire on the computer, asking whether I smoke, whether I drink, how much exercise, etc., but it's a paperwork exercise - they never follow up any of the questions with advice etc. My HBA1C has been rising every time, and is now at a level at which the previous nurse/GP would have increased the medication, but they don't even mention it, let alone do it. At my last appt, a few months ago, I asked what the HBA1C level was, and they gave me a figure, I queried whether my medication needs increasing/changing as it was over the level which previously triggered a change and she just glibly said "maybe we'll look at it next year"!
So, no, the "specialist" diabetic nurses I've dealt with recently don't really seem to have any particular expertise or knowledge and seem happy just to do the form filling and pass me onto someone else next year!