The answer to your question, is it does relatively little. It is a mild drug that is mainly an appetite suppressant. It helps to a limited extent by reducing the amount of glucose the liver produces naturally, but is not to be relied on to bring your overall blood sugars down. You need a reduced carb diet to do that. The common side effects are tummy problems (toilet issues mainly) which affect some people more than others, and usually disappears after a few weeks.
How high are your blood sugars? High BS can and do cause fatigue and tiredness.
Do you have your own blood glucose meter? If not, I highly recommend you buy one. Without one you are working blind. With one you can quickly discover your personal danger foods and also your safe ones.