The metabolic clearance rate (MCR) of radio-labeled growth hormone (GH) was measured in eleven recently diagnosed patients with juvenile-onset diabetes mellitus and in seven healthy nonhospitalized healthy children. The patients with diabetes mellitus demonstrated a significant reduction in MCR of GH as compared to the contrast group. Peripheral GH levels did not reach steady state conditions in the patients with diabetes, thus pituitary production rates of GH could not be evaluated in these patients. It is suggested that diabetes mellitus, even in its earliest clinically apparent stages is associated with a defect in the metabolic clearance of GH. Since the liver has been demonstrated to be the major organ responsible for GH clearance in man, it is evident that diabetes mellitus may be associated with a defect in the hepatic clearance mechanisms for growth hormone.