Antibiotic? I don't know of antibiotics that help diabetes.
Diet and exercise can help control Type 2 (I am ignorant when it comes to the details of Type 1), and meds from your doctor.
Green tea certainly can't hurt and many kinds taste great (my daughter and I are Teavana fans! They have SO many kinds of green tea!). If drinking hot tea when you get the urge to snack helps you control your diet, then go for it. I love a little hot tea in the afternoon. And morning. Sometimes at night...and mid day...
I drink a LOT of tea. Iced, hot, no sweetener, some fake sweetener, sometime with milk, often without...I'm a fan of tea. If green tea could cure or help diabetes, I would be healed by now
Good luck!