The level of the radioimmunological growth hormone, free fatty acids and sugar was determined in the blood on fasting stomach and after the intravenous injection of insulin in 45 patients suffering from diabetes mellitus, insulin-resistant and sensitive, with consideration to body weight. Patients requiring for compensation of diabetes mellitus 100 units and more of insulin per day were referred to the group of resistant cases. A significantly greater growth hormone content on fasting stomach 60 and 120 min after the administration of insulin was found in the sensitive patients with diabetes mellitus with a normal weight, in comparison with the group of healthy individuals; the content was also higher on fasting stomach and in 60 minutes in comparison with the group of sensitive diabetics with excessive weight. A conclusion was drawn on the significance in the resistance formation of prolonged and stable decompensation. A reduction of compensatory possibilities of the hypothalamo-hypophysial system in response to the insulin deficiency in diabetic patients resistant to insulin is supposed. Adiposity characterized by reduction of the insulin sensitivity increased the requirements to the regulating system and led to reduction of the compensatory reaction at the stage of less severe sensitive diabetes. No participation of free fatty acids in the resistance formation was revealed.