Acarbose is an anti-diabetic drug used to treat type 2 diabetes mellitus and, in some countries, prediabetes. Acarbose is an oligosaccharide which is obtained from fermentation processes of a microorganism, Actinoplanes utahensis, and is chemically known as O-4,6-dideoxy¬ 4-[[(1S,4R,5S,6S)-4,5,6-trihydroxy-3-(hydroxymethyl)-2-cyclohexen-1-yl]amino]¬ α-D-glucopyranosyl-(1 → 4)-O-α-D-glucopyranosyl-(1 → 4)-D-glucose. Acarbose is a complex oligosaccharide that delays the digestion of ingested carbohydrates, thereby resulting in a smaller rise in blood glucose concentration following meals. As a consequence of plasma glucose reduction, PRECOSE (acarbose tablets) reduces levels of glycosylated hemoglobin in patients with type 2 diabetes mellitus. Systemic non-enzymatic protein glycosylation, as reflected by levels of glycosylated hemoglobin, is a function of average blood glucose concentration over time. In contrast to sulfonylureas, PRECOSE does not enhance insulin secretion. The antihyperglycemic action of acarbose results from a competitive, reversible inhibition of pancreatic alpha-amylase and membrane-bound intestinal alpha-glucoside hydrolase enzymes. Pancreatic alpha-amylase hydrolyzes complex starches to oligosaccharides in the lumen of the small intestine, while the membrane-bound intestinal alpha-glucosidases hydrolyze oligosaccharides, trisaccharides, and disaccharides to glucose and other monosaccharides in the brush border of the small intestine. In diabetic patients, this enzyme inhibition results in a delayed glucose absorption and a lowering of postprandial hyperglycemia. Because its mechanism of action is different, the effect of PRECOSE to enhance glycemic control is additive to that of sulfonylureas, insulin or metformin when used in combination. In addition, PRECOSE diminishes the insulinotropic and weight-increasing effects of sulfonylureas. Acarbose has no inhibitory activity against lactase and consequently would not be expected to induce lactose intolerance.