About Autism Diagnosis Adult I think I'm autistic - what do I do? If you think that you may be autistic the first port of call will be your General Practitioner (GP). After the initial appointment your GP may decide to refer you on to an autism diagnostic pathway or a different pathway if appropriate. Before the appointment, make a list of all of the things that make you think you could be autistic. It could also be useful to put together a timeline of key dates, as it can be difficult to think back in time.