Probably visiting other hospitals in the same area, visiting their diabetes clinic and asking the right questions to find out what services are on offer and how they deliver them
You won't be alone so don't worry! There will be eg a D consultant and maybe a Paediatric DSN, or another Dr, or all of them from different places who will be doing the same as you, but from their own professional POV.
You will get paperwork upfront basically telling you what they are sposed to have in an ideal world. Then from the hosp you are visiting you will get a another ream of paper as a PDF (it's presented in a table which I had to expand to 200% to read cos they are A3 and nobody's computer screen is) - outlining what they do and how they do it, you will have queries on it - there will be gaps, things missing you don't think there ought to be - eg no psychologist or something - so you write them down and keep your notes with you.
You meet in a room provided on the day, don your ID and gather in your team and introduce yourselves then discuss briefly what you want to see - and then sally forth to meet the staff. They do a little informal presentation to you of their services, and show you round and you can cross examine any of them or pounce on anything new to you and just generally get to know EVERYTHING LOL
Then you go back into a huddle and do your report. There's a format and all the major points are listed, you plod through and can just tick boxes Yes they have this, no they don't - and add comments as appropriate.
Then whoever is in charge from the auditing body goes through your form and asks questions if they need to - they have to put it in the format they need for the full report on the hospital. Cos it isn't just childrens D services that will be being reviewed that day, it will be more than one department, all by different teams.
It's quite a hectic day actually, but it opens your eyes to the other side, as a User. Very enjoyable I found it, but did feel I'd like to do another one soon as I now thought I knew what I was supposed to be doing! No opportunities came up except one too far away from me. It can be a little 'in at the deep end' so I asked the others on my team to explain stuff, the Consultant was a bit of an arse because he was young ,supercilious and talked down to me! (and I wanted to smack him) but the others treated me with respect and DID explain it. Main man said What shall we put here? and then wrote what he wanted, so I argued and said No - they didn't say that at all, they said whatever and you aren't going to leave it like that are you? The others agreed with me so he had no option tee hee hee.
Don't be afraid to put your oar in, we were all supposed to be equal and sometimes you have to insist on it.
Eventually you get a copy of the actual report and you proof read your bit and see if you agree what it says is what you actually found, if it doesn't, or you don't understand something, query it. They have to respond to the queries and explain, you discuss it and hopefully eventually you are happy with it and say so.
Any remedial actions required are put into Action Points.
You finally get a letter telling you what happened when they presented the thing to whoevers running the hospital so it isn't finished when you go home that evening.
You will actually enjoy it believe it or not, but it IS definitely WORK.