Red Cell Oxygen Release Capacity in Untreated Diabetics

Abstract

Studies were conducted to determine whether there is a decrease in oxygen release capacity or not in diabetic patients with an increase of glycosylated hemoglobin (HbA1c). 37 diabetics who had not undergone any treatment and who had high levels of HbA1c were used as subjects for this study. 14 patients out of the 37 diabetics had mild background retinopathy and 23 patients had no retinopathy. None of them were acidotic or anemic. 31 nondiabetic healthy volunteers were used as normal control subjects. The P50 of the oxyhemoglobin dissociation curve at in vivo pH among the 37 diabetics was significantly higher than in the normal control subjects (25. l±1.4mmHg (M±SD) vs. 23.9±1.9 mmHg, P 0.01). The P50 pH 7.4, venous pH and 2, 3 DPG were also significantly higher in the diabetics. There was a significantly positive correlation between the 2,3 DPG and P50 in vivo pH or P50 pH 7.4 in the diabetic group (r=0.42, P <0.01; r -0.46, P < 0.001, respectively). On the other hand, an inverse correlation existed between the hemoglobin concentration and 2,3 DPG in both groups respectively (diabetics: r = -0.59, P<0.001; controls: r-=-0. 53, P<0.005). In all subjects of both groups, HbA1c had a slightly positive relation to venous pH, 2, 3 DPG and P50 in vivo pH. It is concluded that the P50 in vivo pH can be maintained at above normal levels with increase of 2, 3-DPG, so that affinity hypoxia does not occur in untreated diabetics who have high levels of HbA1c and mild background retinopathy or no retinopathy. © 1984, THE JAPAN DIABETES SOCIETY. All rights reserved.