I don't know if they use the definition right here, but by definition GID is not being transgendered, it's being upset about being transgendered.
If they get a sex change, change their appearance, or whatever, and don't feel bad about it anymore, it's not a disorder anymore.
Quick diagnostic criteria grab from Wiki: * Strong and persistent cross-gender identification [...] * Persistent discomfort about one's assigned sex or a sense of inappropriateness in the gender-role of that sex * The diagnosis is not made if the individual has a concurrent physical intersex condition [...] * Clinically significant distress or impairment in social, occupational, or other important areas of functioning.