Hyperlipoproteinemia, diabetes, and oxygen affinity of hemoglobin

Abstract

Oxyhemoglobin dissociation curves (ODC) were performed on blood from diabetic and nondiabetic subjects with and without hypertriglyceridemia. P 50 at in vivo pH was slightly lower than normal in normolipemic diabetics (25.7 versus 26.6 mmHg, p < 0.05), in spite of increased red cell 2,3-diphosphoglycerate concentration (15.4 versus 14.4 μmole/g Hg, p < 0.025). P 50 at in vivo pH in diabetics with moderately elevated very low density lipoproteins (VLDL) — Type IV hyperlipoproteinemia (HLP) — was likewise found to be slightly lower than normal (25.5 versus 26.6 mmHg, p < 0.05). In contrast, diabetics with pronounced hyperlipemia due to accumulation of chylomicrons (type I HLP) or due to accumulation of chylomicrons as well as VLDL (type V HLP) showed markedly increased hemoglobin-oxygen affinity (P 50: 21.1 versus 26.6 mmHg, p < 0.001). The change in the ODC of normolipemic diabetics is considered to be an expression of the presence of an increased proportion of a hemoglobin fraction (Hb A k) with increased oxygen affinity. The additional change in the ODC of the hyperlipemic patients is thought to be secondary to accumulation of triglyceride-rich particles for the following reasons: (1) a similar increase in oxygen affinity of hemoglobin was demonstrated in familial type I HLP of nondiabetic subjects; (2) normal red cells increased their oxygen affinity when incubated in lactescent plasma; (3) in both acquired types I and V HLP the disappearance of HLP was followed by a normalization of the ODC.