Effect of Tolbutamide on Renal Glucose Reabsorption

In sixteen patients, thirteen examinations were carried out after intravenous administration of 1 gm. of tolbutamide, including measurements of insulin clearance and glucose T_mG before and after administration. Furthermore, four examinations were performed with administration of 1 gm. of tolbutamide daily over periods from fourteen days to 160 days. No alterations in insulin clearance were found. The changes in glucose T_MGpresented fairly large individual variations and increases between 20 and 30 per cent were observed in a few patients. An average increase of 9.1 per cent was found after intravenous administration and of 4.8 per cent after oral administration. These variations are not significant.