hi there, if frequent urination is the only complaint then don t jump to conclusions aboout having diabetes. There are plenty of reasons for it , more common being increased intake of water, urinary tract infection, climatic conditions etc, what you need to do is get your routine health checkup done which will include your sugar profile and urine exam. This should give you a fair idea about the cause for excessive urination, accordingly you can ignore it or consult with your local GP who will guide you to the further course of action. Vegan diet is absolutely healthy and there is not reason to be anything wrong if you continue your present diet. Take care