Abstract
In order to investigate the effect of smoking on the red cell oxygen transport and release in pregnant diabetic women, 23 smokers and 23 non-smokers were studied in the third trimester. The two groups were comparable with regard to blood glucose regulation, as the median concentration of blood glucose and glycosylated hemoglobin (Hb A1c) did not differ. Red cell 2, 3-diphosphoglycerate (2, 3-DPG) levels were significantly lower in the smokers than in the non-smokers (16.5 vs 17.8 μmol/gHb, p>0.01). P50 of the oxyhemoglobin dissociation curve at actual pH and at pH 7.40 was also significantly lower in the smokers (25.9 vs 26.9 mmHg, p>0.01, and 26.5 vs 27.8 mmHg, p>0.01 respectively). Red cell 2, 3-DPG was significantly correlated with P50 at pH 7.40 (r = 0.73, p>0.001). Arterial oxygen saturation was reduced to the same degree in smokers and in non-smokers, as compared with healthy non-smoking pregnant women and no adaptive increase in the hemoglobin concentration occurred in the pregnant diabetic smokers. The study suggests that smoking in pregnant diabetic women impairs the adaptive increase in 2, 3-DPG associated with diabetes-induced hypoxia.