The content of insulin antagonists (growth hormone, cortisol, catecholamine, DOPA, free fatty acids) was studied in 40 women suffering from diabetes mellitus, including 12 insulin-sensitive and 15 insulin-resistant, and 13 women with freshly diagnosed untreated diabetes. The greatest content of all the insulin antagonists was revealed in the insulin-sensitive patients during the decompensation period. It is assumed that in this period, diabetogenic actions of insulin antagonists create the most favourable conditions for the formation of insulin antagonists create the most favourable conditions for the formation of insulin resistance; this resistance is then maintained by the increased antibody titre due to the elevation of therapeutic insulin doses and lengthy persistence of the high growth hormone level in the insulin-resistant patients. Besides, the high growth hormone content promotes angioretinopathy development. A conclusion is drawn that the content of growth hormone, cortisol, catecholamines, DOPA, or free fatty acids does not serve as the primary factor in the pathogenesis of diabetes mellitus, since at any of the phases of the disease the level of each of them failed to differ from control.