Early admission has nothing to do with having a diploma. All undergraduate and graduate programs let you apply before you have finished the previous level because the application and acceptance process takes more than the time between schools.
In cases where diplomas are required, the acceptance letter will always contain language stating that they will retract your acceptance if your grades drop an unacceptable amount or you don't finish the degree you're working on. Then most schools require you to submit another set of transcripts, proof of graduation, etc. before you officially enroll.
In cases where diplomas are required, the acceptance letter will always contain language stating that they will retract your acceptance if your grades drop an unacceptable amount or you don't finish the degree you're working on. Then most schools require you to submit another set of transcripts, proof of graduation, etc. before you officially enroll.