Partner has Autism and I need some advice

Hello, my partner has been diagnosed with Autism a few months ago he is 38 but has lived most of his life knowing he is on the spectrum. 

The specialist said he needs to be tested for coeliac disease as well as he struggles a lot with his stomach and she said it can be common with autism.

He also struggles a lot with his sleep and the specialist said practicing good sleep hygiene would help and not using electronics after a certain time because of blue light. 

After the appointment i found some information on sleep hygiene and not just loads of text as i know that would of overwhelmed him as and he wouldn't of read it but it was a simple visual guide and he seemed uninterested so i didn't push it.

I tried to ask about when he can go for the coeliac test and he just said he is not being one of those people who gives up gluten.

He is always saying how bad he is sleeping so i asked if he had been doing the sleep hygiene and he says no because he knows his body better than anyone else does.

Now I'm just afraid to even try because he is always immediately so defensive when I try to help. 

I really would like to know if there is anything I can do. 

Thank you