At the prediabetic stage it is easily controlled and corrected by diet change. But that is not how the medical community approaches it.

Cut out the foods and frequency of eating/drinking them that causes constant high insulin levels which over time causes insulin resistance which over time leads to metabolic syndrome and eventually if not corrected leads often times to type II diabetes not to mention obesity (because insulin tells the body to store fat and constant high insulin levels prevents the normal fat burning from previously stored energy stores of fat).