I have not been diagnosed just randomly took BS it was 400 I don't want to take medication can I reduce it by diet alone
Welcome to the forums
@Reboyd1 . With a reading like that (22 mmol/L in UK units) you should really see a medical practitioner, as that is dangerously high. (Though if you hadn't washed your hands properly before the test it could be an error). If you have T2 diabetes (and that is a big if) it is possible that you may be able to reduce your levels by low carbing, but you need a medical appointment to diagnose. (eg if you have T1 or LADA then you need insulin or you will die.) And there are probably other things than diabetes that cause high bgs so you really need a diagnosis from a doctor, not a forum.
If it turns out that you have T2 then these forums have lots of advice on how to reduce your levels via diet, (though it may be a good idea to take some meds as well, at least at first.)
Please please see a medical professional.
Also, your question would probably get more attention if I moved it to its own thread for you. Would you like me or another mod to do this?