The problem of tissue oxygenation in diabetes mellitus

In order to study the determining factors for oxygen transport the oxyhaemoglobin dissociation curve (ODC), red cell 2,3-diphosphoglycerate (2,3-DPG), and plasma inorganic phosphate were estimated in insulin-requiring juvenile and adult diabetics in various conditions of metabolic control. 2,3-DPG has been shown to vary much more in diabetics than in normals, depending upon the state of metabolic control. These fluctuations of 2,3-DPG are mediated by variations in plasma inorganic phosphate as indicated by a close correlation. While 2,3-DPG was markedly decreased in diabetic ketoacidosis, it tended to be increased in ambulatory, non-acidotic patients. Since in the non-acidotic patients the oxygen-carrying capacity, i.e. the haemoglobin concentration was simultaneously elevated, these findings suggest the presence of relative tissue hypoxia in diabetes. Both in non-acidotic and in ketoacidotic patients there was a strong correlation between the amount of 2,3-DPG and the P50 at actual pH as an experssion of the oxygen affinity of haemoglobin. In order to guarantee an optimal erythrocyte oxygen release in diabetics the content of red cell 2,3-DPG and plasma inorganic phosphate should be higher than normal.