OK, I also thought you were impolite (" I don't know hat that previous poster was talking about"). But what I replied also referenced Rillum, who said I was "confusing the issue". Actually, as you now agree, I wasn't. What is aid was true. The point is that your symptoms are not typical. There still may be something else going on.
So let's put it behind us. My point was only that you have many symptoms which are not typical of untreated diabetes - like putting on weight now, for example. So, yes, an endo may be able to find out what it is. I do hope so because the heart and circulation symptoms sound really quite alarming. And I hope you have something much easier to deal with than diabetes!
The other point is that thyroid problems and diabetes often go together because they are both actually symptoms of an underlying autoimmune disorder, rather than each being a "disease in itself". And they co-occur with a lot of other autoimmune disorders like rheumatoid arthritis, lupus, schizophrenia, bipolar, coeliac disease, pernicious anemia, etc, etc. Because of the historical perception of the body having separate systems (a convenient fiction, which leads to an othopaedic doctor treating one aspect of an autoimmune disease, while an endocrinologist treats another, etc.), autoimmune diseases can take a while to diagnose correctly.
And that's why I asked about your family's history and your long term low weight and you eating habits. So, for example, your low weight could be associated with coeliac, which would also immediately be alleviated by low-carbing........
I am not a doctor, but your endo should take a very, very extensive family and personal history because your symptoms are not straightforward.