The previous observations that IP insulin administration in human T1DM patients results in lower Hba1c, less glycaemic variability and higher IGF‐1 levels as compared to SC insulin treatment 19, 24, 33 led to the hypothesis tested in this study that IP insulin therapy per se would have beneficial effect on the redox status as compared to SC insulin. The gene discussed is IGF1; the disease is type 1 diabetes mellitus.