for your information here is the eligibility criteria for GATE(through which you can get admission into M.TEch courses) and MCA is one of them so you are eligible for M.Tech

ELIGIBILITY FOR GATE
The following categories of candidates are eligible to appear in GATE :

   1. Bachelor
      degree holders in Engineering/Technology/Architecture (4 years after
      10+2) and those who are in the final or pre-final year of such
      programmes.

   2. Master
      degree holders in any branch of Science/Mathematics/Statistics/Computer
      Applications or equivalent and those who are in the final or pre-final
      year of such programmes.

   3. Candidates
      in the second or higher year of the Four-year Integrated Master degree
      programme (Post-B.Sc.) in Engineering/Technology or in the third or
      higher year of Five-year Integrated Master degree programme and Dual
      Degree programme in Engineering/Technology.

   4. Candidates
      with qualifications obtained through examinations conducted by
      professional societies recognised by UPSC/AICTE (e.g. AMIE by
      IE(I), AMICE(I) by the Institute of Civil Engineers (India)-ICE(I)) as
      equivalent to B.E./B.Tech. Those who have completed section A or
      equivalent of such professional courses are also eligible.

From which university you took MCA after diploma. I also want to take. I am also a diploma holder  ( 10+2+3(polytechnic diploma)) and I have 5 years experience. Pls reply.