Acarbose delays the production of monosaccharides (notably glucose) by inhibiting the α-glucosidases associated with the brush-border membrane of the small intestine which are responsible for the digestion of complex polysaccharides and sucrose. In healthy subjects acarbose 100 to 200mg significantly inhibits postprandial glucose, insulin and triglyceride responses, with some evidence of carbohydrate malabsorption with the higher dose.

Clinical trials in patients with non-insulin-dependent diabetes mellitus showed that acarbose improved diabetic control, especially postprandial blood glucose levels, independent of whether the patients were receiving concomitant oral antidiabetic drugs in addition to dietary management. In comparative studies acarbose was significantly superior to placebo, and comparable to biguanides, when used alone or as an adjuvant to sulphonylurea therapy. Trials in patients requiring insulin to control their diabetes demonstrated that acarbose significantly reduced postprandial blood glucose concentrations, resulting in a smoother diurnal blood glucose-time curve and improved symptoms associated with nocturnal hypoglycaemia. Daily insulin requirements were sometimes reduced. In large multicentre trials acarbose up to 600 mg/day for 3 to 12 months improved glycaemic control in approximately 55% of patients with non-insulin-dependent or insulin-dependent diabetes mellitus.

Apart from its use in diabetes, encouraging preliminary results have been obtained with acarbose in other therapeutic areas such as dumping syndrome, reactive hypoglycaemia, and types IIb and IV hyperlipoproteinaemias — however, further clinical experience is needed in these settings before clear conclusions can be drawn.

No serious side effects have been reported during treatment with acarbose, although it is associated with a high incidence of troublesome gastrointestinal symptoms such as flatulence, abdominal distension, borborygmus and diarrhoea. The incidence of these reactions usually decreases with time.

Thus, acarbose represents the first of a new class of oral antidiabetic drugs — the α-glucosidase inhibitors. It has proven useful for improving glycaemic control when used as an adjunct to standard therapy involving dietary restriction, oral antidiabetic drugs and/or subcutaneous insulin. That being the case, acarbose should provide the clinician with an interesting treatment option which can be used in a broad range of patients with diabetes mellitus in whom ‘traditional’ management approaches produce suboptimal glycaemic control.

Acarbose is a complex oligosaccharide which reversibly inhibits α-glucosidases present in the brush-border of the small intestinal mucosa. It has a rank order of inhibitory potency of glucoamylase > sucrase > maltase > isomaltase. The net effect of acarbose-induced inhibition of α-glucosidases is a slowing down in the rate at which complex polysaccharides and sucrose are digested and a subsequent delay in the absorption of glucose. In one study involving 12 healthy volunteers the extent of sucrose absorption was 90% within 200 minutes under control conditions and 60% within 400 minutes following administration of acarbose 100mg.

Studies in rodents and in healthy volunteers have clearly shown that acarbose reduces postprandial hyperglycaemia and plasma insulin concentrations. In healthy subjects the reductions in plasma insulin concentrations were dose dependent, while strict dose-dependency was not always observed for decreases in …