Blood sugar changes were studied in anesthetized dogs before and after pancreatectomy, which was carried out in two stages, the latter being relatively atraumatic. The blood sugar remained normal for 1.5 to 4 hrs. after total pancreatectomy, then increased to the diabetic level. Comparison of glucose tolerance before and immediately after acute pancreatectomy revealed no significant change by either intravenous or intraduodenal route. Thus, a sudden cessation of insulin supply does not necessarily result in immediate hyperglycemia. A normal glucose tolerance appears possible temporarily in the absence of any increase in insulin secretion.