In the US 6.5 and above is considered diabetic on the a1c. 5.7 is in the pre-diabetic range but make no mistake about it damage is being done to your body, even at 5.7 and unless you take action to keep this under control, you will develop insulin resistance and eventually diabetes. 70% of American adults are now in pre-diabetes with an a1c between 5.0 and 6.9. This is going to break the American medical and insurance systems. The number 1 cause of obesity and type 2 diabetes is grain consumption, especially wheat. Americans are now consuming an average of about a half pound of wheat per person, per day. Obesity and diabetes follows wheat consumption. This is a fact. Wheat is the highest glycemic food we consume other than dried fruit, period.
Good books:
The Blood Sugar Solution by Mark Hyman, MD
Wheat Belly by William Davis, MD
What Makes Us Fat by Gary Taubes