To determine the cellular mechanisms by which IGF-I stimulates glucose utilization. The investigator will use the glucose clamp technique in combination with indirect calorimetry and muscle biopsies to quantitate at the whole body level and in muscle the effect of acute IV IGF-I administration on glucose transport, glucose phosphorlation, glycogen synthesis and glucose oxidation. The action of IGF-I on cellular metabilism will be contrasted with a dose of insulin which causes a similar stimulation of whole body glucose disposal in nondiabetic subjects. Studies will be performed in control and insulin resistant non-insulin dependent diabetic subjects. This will help to define the basic cellular mechanism by which IGF-I stimulates glucose disposal in healthy and NIDD subjects.