How can I become a diabetologist without MBBS?

You can't. You need an MBBS degree to prescribe allopathic medicine. You can pursue other alternatives like diabetes management and metabolic care through Ayurvedic, Homeopathy or AYUSH channels.

In India, becoming a diabetologist without an MBBS degree is not possible, as the minimum qualification to practice Medicine and specialize in any medical field, including diabetology, is an MBBS degree. The MBBS degree is a prerequisite for further specialization in medical fields.