Alpha-glucosidase inhibitors, such as acarbose, act as competitive inhibitors of the alpha glucosidases, thereby delaying glucose absorption. This effect on glucose uptake decreases glucose peak and insulin response postprandially and moderately lowers fasting plasma glucose levels and HbA1C, but gastrointestinal adverse effects and the requirement for three times daily dosing may inhibit adherence to therapy. Monotherapy with alpha-glucosidase inhibitors have been associated with HbA1C reductions of between 0.5% and 0.8%, with no weight gain.