Percent Hb A1c in RBC fractions harvested from the top and bottom of the DEP oil, as a function of RBC yield. ●, RBCs with δ less than 1.117, harvested from the top of the oil; ○, RBCs with δ more than 1.117, harvested from the pellets under the oil. The panels represent the 3 patterns observed in the 9 experiments of this series. The only significant difference is in the extent of reversal in the pattern of declining Hb A1c with decreasing yield of light RBCs, which is analyzed in the text. The dotted lines in panels B and C represent extrapolated Hb A1c values at vanishingly small yields, pointing to the values expected among the youngest RBC fractions (lowest Hb A1c) and oldest RBC fractions (calres cells, highest Hb A1c).