Erythrocyte insulin receptor: normalization of binding data for the average cell age by the red cell creatine determination in obese, diabetic and acromegalic patients.

Insulin binding studies performed in erythrocytes (RBC) have been employed in clinical studies assessing the status of insulin receptors at target cell tissues. However, some authors challenged this assumption on the basis of some discrepancies described in comparative studies of other cell types, probably related to populations of different cell age affecting insulin binding to RBC. We evaluated insulin binding to RBC in normal males (n = 10), non-obese diabetic males (n = 13), normal females (n = 15), obese (n = 11) and acromegalic females (n = 5), before and after correction of insulin binding data for creatine concentration in the RBC as a procedure of correction for age, since a negative correlation was described between creatine content and RBC age which also correlates inversely with % insulin binding. Insulin binding in all three groups of patients was not statistically different from corresponding values for normal males and females respectively before correction of data for creatine, but significantly reduced values were found after adjustment for creatine in accordance with published data concerning monocytes. In conclusions, the procedure of correcting insulin binding in erythrocytes by the creatine content in RBC is potentially useful for clinical investigations, since the influence of RBC age is excluded.