Medical errors are the third most common cause of death in the US. Let's just say this is strong evidence that not all doctors know how to do all that doctor-related stuff. Some of them just charge you through the nose and hope that you won't die.
The absolute worst thing I can eat is potatoes - their GI is higher than that of pure glucose, and sure enough I'll hypo only 30 minutes after eating them!
I spent a lot of time reading about and testing various things to see if they could allow me to eat carbs while keeping my blood sugar down. I tried cinnamon, but found no difference in my blood sugar readings (but cinnamon tea is quite delicious!).
The only thing I found that reduced my blood sugar was turmeric. Problem is that when it reduces your blood sugar is quite unpredictable, and actually caused me to hypo quite badly (I presume it depends on what else you eat).
My dad is diabetic and his doctor told him that cinnamon is good for blood sugar levels. It's not in this study though.
He was also told to avoid rice and potatoes. He manages quite well and the doctors are astonished at his low blood sugar measurements every day.