Diabetes and mood swings destroying my life?

I'm a regular guy who gets extremely angry and pissed off when my blood sugar gets high...like around 200-300. I get depressed and don't care about anything, not even my family, girlfriend or myself when my blood sugar is that high. It's like getting tunnel vision and can't see anything in my mind but doom and gloom. I treat my girlfriend like dirt when i'm like that and im sick of it but i can't seem to help it. I just want to run away and die all the time. I literally hate life and have been like this as long as i can remember. I have been diagnosed with type 2 diabetes but my girlfriend says she doesn't act that way when her blood sugar gets high and now that i think of it neither do my parents who are both diabetics as well. So, i'm wondering is there something else that could be connected to my psychotic episodes when my blood sugar is out of control. I use insulin to help control my blood sugar but my mood swings are getting the best of me.