think you've got to gently address this with your wife...if we encounter something that we don't 'normally' see & it is a bit shocking to us, it's natural to be affronted by it. i expect your wife doesn't realise or hasn't really thought about it...perhaps you could ask her what she thinks her work colleague should do, be made to go off to the toilet to inject? then she may realise it's not all that easy to hide away!
i think bringing these things out in the open for discussion with others who don't 'get' it is a fab way to address these issues. it's not their fault as such, they've never had to consider it before like those who have to do these things do (mouthful!)
there may have been a time when i saw a lady breastfeeding her baby 'out in public' and thought 'well, that's a bit OUT THERE' and raised me eyebrows or looked away. but after HAVING to feed 2 babies with my own boobs (ha, i said it!) i realise the other side of it...why on earth should i go to a stinky dirty old toilet to feed my child!??! there are discreet ways to go about these things.
my mum has been a t1 for 37 years, and she used to used syringes. she would never have dreamt of injecting in public. then i got it and i never had to use a syringe, it's all done by fancy 'pens' now where you can be a bit more discreet, no 'drawing up'. i have never made a big thing of it and always just popped my insulin in quietly. my mum got a new lease of life and was happy to be able to be free and not have to hide. i feel a bit conscious sometimes, because if we are together eating out, i think omg, everyone must think we are some kind of diabetic freak show!!!!! but we are both discreet about it, and no one really notices.
i must admit every now & again i do turn away or even go to the loo to inject if i'm feeling a bit intimidated. but i do realise this is MY problem not other peoples. there were also times when i took bottles out instead of breastfeeding because i felt self-conscious. i am mad with myself now, because again it was MY problem, no-one elses.
i hope you never have to feel like you have to hide. why should you? you've done nothing wrong! please bring this up with your wife and let us know how it goes.
it's up to us to be bold and not hide to hopefully challenge peoples ideas of what is acceptable.