Insulin can influence rates of glucose utilization by muscle and possibly other tissues via both direct and indirect effects. It can control the rate of fatty acid mobilization from adipose tissue and the rate of fatty acid oxidation in muscle, and the latter inhibits glucose utilization and oxidation. Insulin may influence the levels of insulin-like growth factors I and II, both of which have effects on rates of glucose utilization by muscle. The inter-tissue cycle between glucose and lactate-the Cori cycle, which is influenced by insulin-may provide another novel mechanism for control of blood glucose. How far other anti-insulin hormones affect these processes is not clear.