For me, one of the biggest things that helped in normalizing blood sugar was lowering body iron stores. As with so many degenerative diseases, high iron is present in diabetes, and the iron itself is causal. You should consider getting an iron panel with TSAT and ferritin. Blood sugar regulation really improved as I got near deficiency, as did energy and mental clarity. This is discussed many places on the forum, as well as in the work of E.D. Weinberg and Dr. Fachinni. Even so called "high normal" ferritin levels can cause blood sugar and other issues, so don't just pay attention to lab ranges.
Magnesium supplementation also seemed to help lower high blood sugar levels, but it was not as dramatic as getting my iron levels near deficiency.
Did you ever worry about hitting anaemic conditions though?