It will go away after pregnancy. Sometimes right after the placenta is delivered, although it takes a few days for some women. In all likelihood- it will go away right after your placenta is out.
There is also a belief that women who have had gestational diabetes that they will go onto develop type 2 later in life. This also isn't true. My dietician and OB have both told me that this isn't true. Gestational Diabetes DOES NOT cause someone to develop type 2 later in life. It does however, show you you have a tendency towards diabetes sooo if you eat a diet full of sugar and never exercise your chances will go up... but that is true for ANYONE, not just women who have had GD.