This thesis reports the effects of the Glucose Tolerance Factor (GTF) on the stimulation of 2-deoxyglucose (2-DG) transport in 3T3-L1 adipocytes and in L6 myotubes. The maximal effects on 2-DG transport in adipocytes were observed at concentrations of 133 nM insulin. The maximal effect of GTF was seen at 20 mg/ml in 3T3-L1 fat cells while maximal stimulation of GTF was seen in L6 myotubes at 50 mg/ml.  These observations indicated that GTF had similar effects to insulin in stimulating glucose uptake in 3T3-L1 adipocytes and in L6 myotubes. Also, GTF works in an additive manner with insulin giving a higher stimulation in glucose transport without interfering with insulin binding to its receptor. GTF's mode of action is not through the phosphorylation of the insulin receptor β chain. However, GTF seems to stimulate phosphorylation of downstream signals such as the IRS-1. (Abstract shortened by UMI.)