Hi
@DJA-440 I think the most important thing is the correct diagnosis. They have given you insulin which suggests they suspect you are a type 1 If it turns out you are ultimately a type 2 then diet will become absolute key. I would be very wary at the moment about going very low carb whilst using insulin.
Many type 1s continue to eat whatever they wish and learn to match their insulin. Others like myself eat carbs in moderation. I would not personally eat cake, biscuits, sweets (apart from my Jelly Babies for hypos) and usually substitute potatoes and pasta. Then there are others who eat keto and use insulin. I personally found this a step too far as I found matching insulin to protein rises too difficult to manage. Be guided by your hospital team until you know more.