Why would you use a needle more than once?
Powerful graphic, I re-use to minimise waste and also to minimise gear I have to carry round....
But when I was a kid my mother was using reusable syringes (nasty things, she splurged to buy me disposable syringes, as the NHS only paid for re-usable syringes) so I guess I'm more used to re-using than the younger folk.
I do still sometimes use syringes (mainly if a pen breaks, mine don't seem to last more than a couple of years), and sometimes because I just can't find my pen
.
Pros to pens
I can just shove one in my bag - small and convenient.
Small cartridges mean that if I suspect my insulin has gone off I can change the cartridge without wasting too much insulin.
Small cartridges mean that I don't have to keep my current supply/pen in the fridge while I'm not using it.
Air bubbles are easier to handle as they don't really happen.
Very discreet for injecting in public.
Less waste compared to syringes (even if you don't re-use)
Cons to pens
They break eventually
Another layer of doubt as to dosage - is my pen broken, did it really deliver the right amount? (Though you can test by putting 20 units into the bottom a a penfill cover.)
If the cartridge inside cracks, it's easy not to notice and deliver less insulin than intended (plus the cartridge has a crack, so insulin is potentially contaminated).
A big mistake if you inject in the evening and mistake your basal and bolus pens (though I guess that happens with insulin vials too).
I prefer pens, but keep some emergency syringes, just in case. My emergency go-bag (am in NZ and have been evacuated twice due to fire in last month, and also have to worry about earthquakes), has syringes in it.