DIABETIC VASCULAR DISEASE:The Importance of Insulin Deficiency, Hyperglycemia and Hypophosphatemia on Red Cell Oxygen Unloading1

Abstract

Diabetes is associated with a fluctuating impairment in oxygen transport of the erythrocytes. This impairment is correlated with hyperglycemia by the formation of glycosylated hemoglobin (HbA,,) and with inhibitory factors of glycolysis i.e. hypophosphatemia and acidosis which lower the concentration of red cell 2,3-diphosphoglycerate. Diabetic angiopathy may be the ultimate result of innumerable microvascular responses to discrete hypoxic injuries associated with increased plasma permeation through the vessel walls. It is shown that two additional risk factors for atherosclerosis-smokg and hypertriglyceridemia may also lead to arterial wall hypoxia by changing the position of the oxyhemoglobm dissociation curve. KEY WORDS: Diabetic angiopathy, red cell oxygen unloading, oxyhemoglobin dissociation curve, 2,3-diphosphoglycerate, plasma inorganic phosphate, insulin Acta Pat-diatr Scand Suppl270 8-77288 I

Photoacoustic Spectroscopy and Hyperglycemia in Experimental Type 1 Diabetes

“…Hyperglycemia induces structural changes of the oxyHb, including the transformation of both heme and the globin. 37 In those conditions, dissociation of oxygen from Hb is affected, 4,38 meaning that there is a reduction of oxygen liberation. This is important because it could implicate that oxyHb, at least during hyperglycemia, could not necessarily indicate an optimum oxygenation.…”

“…HbA1c levels account for the average glycemia in the last three months (half-life of erythrocytes). 4 Long-term diabetes complications, the main cause of death of patients with diabetes, is related to chronic hyperglycemia and high HbA1c. 5 In the treatment for people with type 1 diabetes, it is necessary to inject daily insulin; for type 2, at the beginning oral medications are administered as a first resource, but when it is no longer enough to control hyperglycemia it is necessary to add insulin.…”

The Clinical Value of HbA1‐Determinations

“…Clycosylated hemoglobin has an increased 0,-affinity , resulting in an impaired delivery of O2 to the tissues. According to Ditzel ( 11) this may contribute to tissue hypoxia, especially if the 2,3-diphosphoglycerate level is low. The glycosylation of hemoglobin may also be looked upon as a model for glycosylation of other proteins in tissues not dependent on insulin for their glucose uptake, i.e.…”