Yes you can get admission to direct second year in any degree college. You will have to take admission as a lateral entry student after completing your Diploma. With this you can directly enter to second year of Mechanical Engineering.
Every college has its own eligiblity criteria and minimum cutoff percentage required in your highest qualification. The cutoff percentage varies from college to college. Lateral entry admissions are usually done based upon merit. So you should have a good percentage in your Diploma to get a seat.
You can contact the respective college of your choice in which you want to get admission through lateral entry regarding the admission procedure.
Hope this helps