The chronic nature of type 2 (non-insulin-dependent) diabetes mellitus, and the importance of monitoring and regulating blood glucose levels in order to minimise development of serious and costly diabetic complications, make the disease a prime target for disease management programmes. Although diet and lifestyle modifications are the mainstay of management of type 2 diabetes, fewer than 10% of patients are able to achieve long term glycaemic control without pharmacological intervention.Acarbose is an &agr;-glucosidase inhibitor which delays entry of glucose into the bloodstream after ingestion of complex carbohydrates and disaccharides, by delaying enzymatic breakdown of these foods in the intestine. This results in attenuation of postprandial plasma glucose and insulin peaks and a smoothing of diurnal plasma glucose profiles.In patients with type 2 diabetes managed with diet alone or diet plus other antidiabetic agents, acarbose lowers postprandial plasma glucose levels by approximately 2.2 to 3.3 mmol/L (40 to 60 mg/dl). Glycosylated haemoglobin (HbA1c) is usually lowered by 0.5 to 1%, although the magnitude of the reduction appears to depend on baseline levels, and larger increases have been reported. These changes are accompanied by modest reductions in fasting blood glucose (0.6 to 1.1 mmol/L: 10 to 20 mg/dl), triglyceride and/or total cholesterol levels in some patients. Acarbose may lower HbA1cto a lesser extent than sulphonylureas and metformin, although a small number of studies have indicated similar efficacy. Acarbose has been used successfully in combination with sulphonylureas, metformin and insulin.Acarbose is well tolerated systemically, but causes gastrointestinal disturbances (flatulence, meteorism/borborygmi, diarrhoea) in approximately two-thirds of patients. These symptoms may be marked at the beginning of treatment but can be minimised by careful dosage titration and also tend to subside over time. This relatively benign profile of adverse events is particularly advantageous in patients in whom other oral antidiabetic agents are contraindicated, although some patients may be unable to tolerate the gastrointestinal effects. In contrast to sulphonylureas and insulin, acarbose does not raise plasma insulin levles or promote bodyweight gain and does not cause hypoglycaemia when used as monotherapy.Thus, acarbose is a first-line therapy which can be used in a wide range of patients, in conjunction with diet or with other antidiabetic agents. It may provide an alternative to metformin in patients in whom biguanides are contraindicated and an alternative to sulphonylureas in patients, such as the elderly, in whom hypoglycaemia is particularly dangerous.