 In this double-blind, placebo-controlled study, subjects with prediabetes and type 2 diabetes were randomly assigned to the placebo control group or the test Arginyl-fructose: AF group. We determined fasting serum levels of glucose, hemoglobin A1c HbA1c, insulin, and free fatty acids FFAs, were measured by 2-h oral glucose tolerance tests OGTTs at baseline and after the 6-week intervention. 