It's been 3 years is it him?

So we have a 5 year old daughter who is beautiful and healthy and had a miscarriage 3 years ago...we have been ttc ever since. here's some of our history... everything with 1st pregnancy was perfect. after having our daughter I was diagnosed with thyroid problems and still dealing with now but levels are perfect for conceiving. also after our daughter was born my husband was diagnosed with type 1 diabetes he has been very healthy and takes great care of himself and his sugar levels. we later got pregnant and had a miscarriage at 8 weeks, and have ttc since...my doctors say I'm good to go...but still not getting pregnant could him being diabetic mess with us conceiving?