Dog Peeing in the House at Night?

My dog was diagnosed with diabetes in December 2012. She's on insulin, 2 x a day. At night she pees in the house. I take her out around 10, and sometime she holds it and other times she doesn't. It's getting so frustrating. I know she can hold it, I've seen her. Other times she just goes, even when she was just out 3 hours earlier. I'm not sure if she's just getting lazy or what! The vet just increased her insulin up to 5. Someone help me.

By Mary P