Taking into account the factors mentioned above, the paramount aim of the paper is the quantitative assessment of selected regulatory molecules expression, such as leptin, leptin receptor, and adiponectin in the blood of sick, obese individuals with type 2 diabetes both before treatment, as well as six months after the pharmacological therapy with a long-lasting insulin analogue, insulin detemir. This evidence concerns the gene LEPR and type 2 diabetes mellitus.