The NHS should train medics to prevent autistic people from feeling they get inadequate treatment, an inquiry has found.
A survey of almost 900 autistic people, parents and professionals by The Westminster Commission on Autism found nearly three quarters of respondents felt autistic people receive "worse" or "much worse" treatment than others.
The Autism Act should guarantee the estimated 700,000 people who live with the condition in the UK awareness in the health service, the study says.
It has also called on Health Secretary Jeremy Hunt to remind clinical commissioning groups of obligations to ensure staff have the skills to support autistic people.
The inquiry was founded by Barry Sheerman, the MP for Huddersfield, who has an autistic grandson.
Around three quarters of respondents questioned in the study, which will be published in Parliament on Monday, said medics "rarely" or "never" understand autism and its affects on physical and mental health. Seventy per cent of respondents cited training as the top priority to improve access to healthcare.
Craig Kennady, a commission member with autism, said he left A&E while experiencing breathing difficulties because a misunderstanding with a nurse left him "distressed".
The 32-year-old from Chesterfield, Derbyshire, said: "Every minute that passed by I had flashes of losing my life and not being able to support my wife and my children."
The UK does not have mortality figures for autistic people but a study suggests they die 16 years earlier in Sweden.
The report also calls for GPs to flag up autistic patients so they can be added to an anonymous national register, which could be used to calculate UK mortality statistics.
A Department of Health spokesman said it has been working with the Royal College of General Practitioners to improve GPs' understanding of autism.