I'm not sure about during the day but eating 6-8 ounces green beans (canned is okay) before bedtime will give a better morning reading. The green beans prevent insulin storing in fat at night. I was sceptacle when I read this but every time I do this my morning readings are normal. I will add that I am not on insulin.
Of course there are some whose diabetes is harder to manage than others. Mine isn't raging yet.
I got this information from a holistic doctor and it works for me.