Plasma and Urine Pc-1 Activity in Type 2 Diabetics Treated with Metformin

The plasma cell differentiation antigen (PC-1) is an inhibitor of insulin receptor tyrosine kinase activity and is a major factor of insulin resistance in patients with type 2 diabetes mellitus. We have studied lymphocyte PC-1 (ecto-alkaline phosphodiesterase I, APD I) in obese type 2 diabetics, as well as plasma level and urinary excretion of PC-1. Fifteen patients (8 female, 7 male) with a BMI 34.11±3.37 kg/m, were studied before and after 3 months of metformin (1000 mg b.i.d.) treatment. Lymphocyte PC-1 in patients with type 2 diabetes was markedly increased, and metformin treatment brought it to the level slightly over control. Plasma PC-1 was significantly reduced after metformin treatment, from 37 to 14 mU/L. However, urinary excretion of PC-1 was not changed by metformin treatment. A highly significant correlation between lymphocyte and plasma PC-1 was obtained (r = 0.909 and 0.529, before and after metformin treatment, respectively). Glucoregulation was found improved by metformin treatment as the mean glycosylated hemoglobin was found decreased from 8.15 before to 7.07% after therapy with metformin. In conclusion, an increased lymphocyte PC-1 activity and its reversal by metformin treatment were demonstrated in obese type 2 diabetics. Plasma PC-1 activity was found also decreased after metformin treatment and correlated significantly with lymphocyte PC-1 activity. Urine PC-1 was not found to correlate with lymphocyte PC-1. A high correlation of plasma and lymphocyte PC-1 before metformin treatment should be evaluated for using plasma PC-1 in demonstration of insulin resistance in type 2 diabetics. Plasma but not urine PC-1 correlates with insulin resistance in obese type 2 diabetes mellitus.