hi,

see candidates are eligible to study diploma in engineering after completing 10th with mathematics, and sciences. however you have an added advantage that you have studied 12th as well. now the basics knowledge which would help you for studies from 12th course is mathematics, specially algebra, differentiation, Integration, functions, from physics, current electricity, electromagnetic theory, modern physics, boolean algebra, logic  gates, etc.

refer to the below link to know about the state of up, diploma in electronics engineering syllabus, which would help you to know about the subjects as a reference:

http://bteup.ac.in/Syllabus/folder1920/330%20NSQF%20NITTR.pdf