One of the things you can do is become your own expert as said everybody has a different way of managing their blood glucose levels as they are an individual and the way their body responds to the carbohydrates they eat will not be the same as Mrs M down the road.
The Learning Zone here is a good start to give you a better understanding and also this link gives an approach which was developed by that surgery and adopts the principals many here have found successful and might give you a way forward to modifying your dietary regime.
https://lowcarbfreshwell.co.uk/
Many who get a diagnosis it comes out of the blue but others do have a suspicion that there is something not right. But many do look upon it as an opportunity to make lifestyle changes for the better but it is a pity that the support is often lacking, more so now with the intense pressure on G Ps.
It comes down to the individual to arm themselves with with the tools available to bring down blood glucose levels. Iit is no good just taking the medication and expecting that to be enough without making dietary changes and the tools to enable you to know if those changes are working is testing with a home glucose monitor.
Many people are under the misapprehension that it is only sugar and sugary things you need to avoid but testing will quickly reveal that it is much more than that as ALL carbohydrates convert to glucose so cutting out or down on other things are also needed.
However going about it logically and gradually is better as you will be less likely to get issues with your eyes or nerves and how much you need to do will depend on how high your HbA1C is so if only just in the diabetic zone, a little way over 48mmol/mol then some modest changes may be sufficient but if very high then you may have been given medication which with some more stringent dietary change be be needed.
Do you know what your HbA1C is and are you taking any medication as that could affect what approach would be sensible.
Keeping a food diary and estimating the amount of TOTAL carbohydrate your are having and then reducing by one third for a couple of weeks, then another third until you get to where you need to be.
Many people find a low carb dietary regime very successful and that would be less than 130g per day. Making sure you have meals based on protein, healthy fats and vegetables and salads and fruits like berries will still give you options for tasty meals.
A often quoted phrase is getting good blood glucose management is a marathon not a sprint.