Since the redox reactions of H2O2 or conversion of glucose are pH dependent  it is better to use buffer solution. You will get a sensor response as well in Na2SO4 electrolyte solution, but it could be less reliable for example during long-term operation. When you use an enzymatical catalized reaction for sensing, then it is stongly recommended to use the buffer solution.

Thanks Nataliya for your precious information.

• I agree with Nataliya. Also during determination H+ produced from electrolysisis may for H2S which change pH and degenerate electrode surface. Should use buffer