From Hypo- to Hyperthyroidism

Something odd happened to me recently: I tested positive for Graves Disease.

This is really interesting since I was hypothyroid for 17 years and then in the past year noticed my TSH near rock bottom [signifying hyperthyroidism].

Yes, Graves Disease is autoimmune. [No surprise there, right?]

Has anyone else with Type 2 Diabetes and thyroid issues seen a flip/flop? Do you know what caused it?