NON-INSULIN-DEPENDENT DIABETIC-PATIENTS HAVE INCREASED GLUCOSE-UPTAKE IN RED-BLOOD-CELLS

The kinetic characteristics of 3-O-methyl glucose (3-OMG) uptake were examined in red blood cells (RBC) from seven normal individuals (controls) and nine patients with non-insulin-dependent diabetes mellitus (NIDDM) treated with diet and oral hypoglycemic medication. Comparison of rates of 3-OMG uptake at 5 different substrate concentrations revealed significantly higher overall 3-OMG uptake in the diabetic group (P < 0.0001). Kinetic parameters obtained for individual subjects showed there was not a significant difference in the K(m) between the diabetic (3.17 +/- 0.45 mM; mean +/- SE) and the control (2.46 +/- 0.25 mM) groups. However, V(max) was significantly increased (61%; P < 0.025) in the diabetics (217.8 +/- 28.9 pmol/2 sec per 10(6) cells) compared to controls (135.2 +/- 15.6 pmol/2 sec per 10(6) cells). There was no correlation between HbA1C levels in the diabetic patients and V(max) values for 3-OMG uptake, suggesting that the increased hexose uptake was not accounted for simply by increased glycosylation in these cells. Glucose transport in RBC in hyperglycemic states may be a useful model for delineating the regulation of the non-insulin-mediated disposal of glucose in diabetes.