SAMPLE SIZE DETERMINATION: Anticipating an absolute change in FPG smaller than what observed in previous studies in patients with T2D, 10 patients with prediabetes in total entering a two-treatment parallel-design study will provide 90% probability of detecting a true between-treatment difference in FPG means of 22 mg/dl with standard deviation of 10 mg/dl, using a paired two-sided comparison with type 1 error of 0.05. To allow for up to 20% dropout, 12 patients in total will be recruited.