It makes me want to look a little harder for other explanations. Although it is possible that this could all occur from the other med's, the syndrome that usually occurs with your med combination involves less gain in the belly, with some lactic acidosis, as well as abdominal pain, fatigue and not feeling well in general. These are questions that you and your doctor might ask. One thing that you mention is the diabetes. If you are not well controlled, this is definitely the first thing to do.
Low testosterone is another potential player.
This is because gains in lean tissue occur in this situation, and people feel much better. The sex drive part works as follows. If you are low on testosterone, and take testosterone replacement, you can expect an increased libido. Everyone is individual in this regard, however, so you may have to try it and see. Exercise is excellent for type 2 diabetes and helps increase muscle mass while reducing belly fat.