Here's how I see it. I know which vitamins I'm deficient in (Iron, Vitamin D, Magnesium, Calcium) - I take a supplement for Vitamin D because it needs to be such a high dosage to get my levels up that I couldn't achieve that with diet and sunshine and whatever alone (plus I'm not really in a position to get out and about for a stroll at the moment). The rest I'm working on through diet. I can't take iron tablets. I mean, I
can but I get such wicked IBS on them (any kind) that I'd rather deal with anaemia!
Since starting a low-carb (and I think this is probably true of most types of diet), I'm eating far more fresh, unprocessed foods, so am getting a far better quality diet - which means far more nourishment. I've increased my veggie intake, have cut out "stodge" - so no more bloaty foods taking up Quality Time with my gut flora. I feel fairly confident that, as long as I continue to maintain a "healthy" balanced (low-carb) diet (a simple variety of veg, meat, fish and dairy - I'm impossibly lazy so this is a zero-effort regime) my next round of bloods will show my iron, magnesium and calcium levels returning to normal - apparently it's quite common for T2's to have these get a bit wonky, as well as slightly wonky Liver Function Test results.
But on top of that:
http://www.hopkinsmedicine.org/heal.../is-there-really-any-benefit-to-multivitamins
You can ask for your vitamin levels to be taken - it's common for diabetics to have slightly wonky levels, as I said, but they straighten out as your diet becomes more suited to what your body needs.
Yes, it's personal choice, but I prefer to spend my money on some nice olive oil and a good cut of meat.