Convert PostreSQL Enum type to Django Customer Field

I have the following ENUM in my PostgreSQL database:

CREATE TYPE UserType AS ENUM ('Admin','Teacher', 'Student');

CREATE TYPE CourseType AS ENUM ();

I want to use this as one of the column-type in my tables, but how do I create this custom field in Django which uses the values in the ENUM type of PostgreSQL and not just use tuples like:

USER_TYPES = (
    ('A', 'Admin'),
    ('T', 'Teacher'),
    ('S', 'Student'),
)
usertype = models.CharField(max_length=1, choices=USER_TYPES)

as this will be locally saved in Django project and not in database. I plan to add more values in this ENUM so want the Django to use this type as a Field and not choices. How do I do that.