Mood Swings and Effect on Relationship

Somewhere in this thread, I noticed someone mentioned how difficult it is to find any information on mood swings and diabetes. I have searched a few times and for whatever reason I found this exchange today, much to my relief.  My husband and I have been married for 15 years but together since high school over  20 years ago.  A few months after our first child was born about 10 years ago - he developed suddenly diabetes.  Without getting into the details and confusion, it was not clear if it was Type 1, Type 2 but he is insulin dependent.  To his credit he immediately adjusted his lifestyle and is under tight control, but of course it is virtually impossible, even being very vigilant, to avoid all lows and highs. He visits his 2 doctors regularly, follows a good diet (most of the time, we are all human) and is very aware of the long-term effects to avoid.  However, since being diagnosed and even more so over the last 5 years it seems to me that he has very severe mood swings, is irritable and impatient - a completely different person than the one I married.  We now have 3 children and I can only explain the drastic personality shift on his diabetes.  I can see his lows and I sympathize with those who say their husband is defensive and angry at the suggestion that he check his bloodsugar.  I also am concerned that he is able to detect them less and less.  Last night though, I am certain that it was a sudden increase that was the reason for his mood - I could hear his mood change in the way that he spoke to the kids and basically fell apart. I convinced him to check his blood sugar being certain it was low, but it was high. 

I am less and less tolerant, and more and more angry, he refuses to acknowledge it, and none of this is good.

Does anyone else have this experience? Or maybe, he really is a different person now and there is no link.