As already mentioned by our friends here, the Diploma holders who have completed 3 year diploma in the relevant field in a recognized Institute like Government Polytechnic are eligible for joining in the II year B Tech/ B E course directly after clearing a Common Entrance Test conducted by the respective State Government agencies. For instance, you have pursued your Diploma in Civil Engineering, then you are entitled to join in II year of B Tech course in Civil Engineering or any other branch related Civil Engineering like Soil management or Ground water technology etc. States like Telengana. AP, Maharastra, Karnataka and others hold a CET exclusively for admission into Engineering colleges for those Diploma holders every year. You can check out for the advertisement and go ahead.