Because I can get away with it..
With say tradespeople doing up my house who are meant to be professionals I will be nicely, politely telling them off.. If my husband did the same sort of thing I know I would call him a plonker...
Or for example... If my old neighbour at 90 told me things ten times, I wouldnt comment....or if I had to tell her something 10 times I wouldnt care... But with my nearest and dearest mum and hubby I hate having to repeat myself.. And I'll tell them 'i've already told you this before'...
My nature, my personality... That to me is my irritation and anger.. but not linked on my being hypo or hyper...
Good suggestion above to tryand find out what his levels are at time of irritation/anger. Or it maybe certain subjects that make him angry...
You say he's lovely and you wanting to help him.. Is he ok with his diabetes? Are you worried about that at all?