At baseline and after the 1st and 3rd exposures of HBOT.T2D patients had significant greater concentrations of HbA1C.T2D patients had significant lower concentrations of IGF-1.After the 1st and 3rd HBOT treatment, T2D patients had significantly greater insulin, leptin and NO serum concentration. The gene discussed is INS; the disease is type 2 diabetes mellitus.