pioglitazone and gliclazide both have weight gain as known side effects. It is likely to be hard to lose weight on them.
One method most doctors won't tell you about is carb control. They concentrate on pharmaceuticals.
Restricing carbs will bring bg down as well as weight.
Certainly Victoza and Byetta both help weight loss and bg control. Probably because of their appetite suppressant properties.
Exercise too doesn't do much for weight loss, although it makes you fitter.
In tests, exercise alone, without diet control has been shown not to reduce weight.