Police launched an appeal yesterday after 15-year-old Emma Burns failed to return to Kibble School in Paisley, where she is a resident.
There was concern that she did not have the specialist equipment that she needs to carry everywhere to help her cope with her condition.
She was reported missing at around 11.45pm on Saturday by a member of staff.
She was last seen at 3.50pm that day. When she failed to return, the alarm was raised.
Inspector Fergus Cook, at Paisley, said that concern was mounting as it was unknown if she had the required medication with her.
Extensive inquiries continued for information about the girl, who was known to frequent Castlemilk, Glasgow city centre and Ayrshire, before she was found.
He had urged the teenager to return to the school or contact police to let them know she was safe and well.
He also said it was "imperative" that she took her medication, and urged anyone who knew her whereabouts to come forward.
It was unclear last night where she was found.
Kibble is one of Scotland's oldest charities and at present operates as a social enterprise.
The school, in Paisley's Goudie Street, works with young people between the ages of five and adulthood who come from difficult backgrounds.
It offers a uniquely integrated array of services to help them play a fulfilling role in society.