Not sure where you live but as I understand it in the UK you are entitled to free prescriptions if you have diabetes. You need to ask to see a different Dr if your glucose is that high and nothing is being done. It amounts to medical negligence and is disastrous for your long term health. Go back and insist on getting some medical help or a referral. I am fortunate in that I was a biochemist so I monitor myself closely (with the odd lapse) and discuss my care with my DN.
A low carb diet had an immediate effect on my BG levels, so I think you might need some reassessment - and perhaps insulin in order to reduce those really rather concerning levels. Six months on a low carb diet and I was no longer in the diabetes or even prediabetes ranges.