diploma pass out student's can take admissions..

Yes, you can join B.Tech program after completing polytechnic in the diploma of engineering. You can take admission in B.Tech through two examinations. One is through lateral entry entrance examination and other is engineering entrance examination.
.For this you have to appear in engineering entrance examination like JEE or any other state level engineering entrance examination. But through this examination you will be able to take admission in 1st year of B.Tech and might be chances that you can get admission in IITs or NITs but for that you need to prepare.
But I think it's better for you to try first for lateral entry examination in this way you will be able to save your one year. If you don't get admission in good college through lateral entry, then only you may try to take admission through engineering entrance examination.

Hope this helps.