DIFFERENT EFFECT OF ACUTE AND CHRONIC ORAL METFORMIN ADMINISTRATION ON GLUCOSE AND INSULIN-RESPONSE TO BREAD AND TO PASTA IN NON-INSULIN-DEPENDENT DIABETIC-PATIENTS

The aim of the study was to evaluate whether acute and chronic metform in administration may influence differently the glycaemic and insulin response to foods with high and low glycaemic index (bread and pasta) in twelve non-insulin dependent diabetic (NIDDM) patients. Thirty minu tes after a random oral administration of either a placebo or a single 850 mg metformin dose, glycaemic and insulin responses to 90 g white bread or 68 g pasta (corresponding to 50 g carbohydrates) were evaluat ed within 4 h. All the patients were subsequently treated with metform in (850 mg twice a day) for a month and then glycaemic and insulin res ponses were evaluated again. The acute administration of metformin low ered glycaemic response to bread at 60 and 90 min (P < 0.02 and P < 0. 05, respectively) but not to pasta, without affecting insulin response . Chronic metformin treatment significantly lowered glycaemic and insu lin response to both bread and pasta. In conclusion, an acute antihype rglycaemic effect of metformin was demonstrable only when a food with high glycaemic index, such as bread, was eaten. On the contrary, the e ffect of chronic treatment was always present, independent from the gl ycaemic index of foods, together with a reduction in insulin response, indicating an enhanced sensitivity to endogenous insulin.