2,3-Diphosphoglycerate and tissue oxygenation in uncontrolled diabetes mellitus.

Abstract In 15 patients with uncontrolled diabetes mellitus, red-cell 2,3-diphos-phoglycerate (2,3-D.P.G.) levels were decreased below the normal range of 4·5±0·5 to 2·2±0·4 mmoles per litre. There was a strong positive correlation of 2,3- D.P.G. with arterial-blood pH and there were negative correlations of 2,3-D.P.G. with blood lactate/ pyruvate (L/P) and total ketone bodies. The lowered 2,3-D.P.G. level balanced the effect of pH on the oxyhaemoglobin-dissociation curve, so that there would be little net effect on tissue-oxygen supply. The raised L/P ratios before treatment could be accounted for by the change in pH without need to postulate tissue anoxia. On treatment 2,3-D.P.G. took up to 5 days to return to normal. It is suggested that this was secondary to a prolonged fall in plasma-phosphate. Patients receiving intravenous bicarbonate showed a rapid correction in blood-pH, together with an acute fall in calculated P 50 (partial pressure at which there is 50% saturation of haemoglobin) and no change in L/P ratio, indicating tissue anoxia, resulting from the low red-cell 2,3-D.P.G. concentration. It is suggested that intravenous regimens for the treatment of uncontrolled diabetes should include phosphate and exclude bicarbonate whenever possible.