I agree with you that the physiologic role played by elevated Hb A1c levels in diabetics regarding oxygen transport can be debated. In the article, I tried to present this only as a point of view, not as clearly established scientific fact. I personally believe that Ditzel's arguments about the interactions of RBC 2,3 diphosphoglycerate (DPG) and hemoglobin in regard to oxygen delivery in the microcirculation are plausible and somewhat compelling. I do agree, however, that more definitive work is needed before we can be certain of the role of an elevated Hb A1c level alone, without changes in RBC DPG, in local tissue oxygen delivery in diabetes.
Glycosylation of numerous proteins may well be of critical importance in diabetic vascular disease, as your letter so nicely points out. Incidentally, workers at our medical school in Columbia, SC, have recently shown that albumin can be added to the list