Effect of age on glucose utilization and responsiveness to insulin in forearm muscle

To determine the effect of age on responsiveness to insulin, 35 healthy subjects (age range, 22--73 years) were studied. A glucose-clamp technique was used to obtain a range of values for steady-state arterial glucose and arterial insulin concentrations; total body glucose utilization was estimated from the rate of glucose infusion needed to maintain the steady state; and the uptake of glucose and insulin by forearm muscle was determined by a forearm perfusion procedure. The results were examined by multiple regression analyses. The rate of glucose utilization by the whole body as well as by forearm muscle was dependent upon the insulin concentration. Age had no apparent effect on body glucose utilization, the uptake of glucose or insulin by muscle, or the steady-state insulin concentration in response to hyperglycemia. It is concluded that the abnormal glucose tolerance commonly associated with increased age is not due to a decrease in either insulin secretion or insulin stimulation of glucose uptake.