Acarbose attenuates basal and postprandial insulin concentrations but fails to lower blood pressure in the spontaneously hypertensive rat

Background: Patients with essential hypertension and the spontaneously hypertensive rat (SHR) are insulin-resistant and hyperinsulinemic. These findings suggest the possibility that insulin resistance and hyperinsulinemia may play a pivotal role in blood pressure regulation. Acarbose, an oral antihyperglycemic drug, decreases hyperinsulinemia and hyperglycemia. The purpose of this study was to assess the influence of acarbose on basal and postprandial insulin and glucose levels and whether changes in beta-cell function result in a change in blood pressure measurements. Methods: SHRs were fed custom diets ad libitum, six with and six without acarbose (40mg/100g of chow). Fasting and postprandial glucose and insulin levels were analyzed following glucose administration (1.75 g/kg body weight). Blood pressure was determined by the tail cuff method. Results: Fasting glucose values were similar, but fasting insulin levels declined 23% in the acarbose treated group (P < .05). Postprandial glucose and insulin levels decreased 18% and 20%, respectively (P < .01), in the acarbose group vs the control animals. Despite the decrease in fasting and postprandial insulin concentrations, systolic, mean, and calculated diastolic blood pressures were insignificantly different in the acarbose group after six weeks of treatment compared to control animals. Conclusion: Acarbose decreases fasting insulin levels and postprandial glucose and insulin levels without effectively lowering blood pressure in the SHR. The ability of acarbose to attenuate the hyperinsulinemic state in the SHR without effectively lowering blood pressure suggests that factors other than serum insulin concentration are important in the modulation of blood pressure.