I am a type 1 diabetic and I was able to successfully nurse both of my sons. My milk analysis showed that my milk was significantly more thick and dense when my sugars were elevated for a prolonged period of time, which they said would make it have a much higher caloric content. My children didn't have an issue with it when it was thick, but I would imagine that , if your baby has a more sensitive tummy, then the hypos could be affecting him/her, or it could be your diet that they're having trouble digesting. Either way, the breastmilk is still easier for a baby to digest, than any formula that's out there. You may just want to watch your diet, sugars, and water intake for a couple of days, and see if that smoothes everything out.
Ooops, I meant hypers, not hypos. Sorry.