Non-invasive glucose monitoring is the most attractive way for people with diabetes. In this paper, we proposed a wearable prototype system for bio-impedance measurement. A tetrapolar Analog-Front-End (4E-AFE) was designed to fully adapt the AD5933 to a four electrode strategy. A normal oral glucose tolerance test (OGTT) in vivo were conducted to investigate the feasibility of the prototype system. The impedance spectroscopy on fingertip within the frequency range of 10 KHz–100 KHz were measured. The characteristic parameters, R0, R∞ α, fc, Re, Ri, of the bio-impedance equivalent model were extracted. Experimental results shows that the characteristic parameter fc is maximum and then decreasing gradually during period of postprandial 0.5h-1h. Lastly, the value of fc is rising again at postprandial 1.5h, which indicate an inverse behavior that might be an expected response for blood glucose levels based on the OGTT.