What Causes Lightheadedness While Having A-fib And Diabetes?

I feel light headed when I stand up, and when I get up in the morning this day. It goes away, and I sit for maybe just a minute, but sometimes it comes back, and it finally goes away. I have A-Fib, and take meds for this. I was diabetic last year 12/15/2014 and did the work...lost 30 pounds with exercise and change in eating habits. I was taken off Metforman March 2014 for doing the work to bring my A1C from 6.2 to 5.0. what is the problem? My DOB is 10-7-1956.