Droplet formation in a microfluidic T-junction is observed in enormous applications. Uniformity in droplet size and its stability are two crucial parameters, which are needed for a myriad of applications. As the dispersed and continuous phases interact near the junction point of the channel, flow instabilities arise due to unbalanced conditions of different forces acting on the droplet. These instabilities result in fluctuating pressure, which further affects the droplet formation process. In the present work, pressure characteristics during droplet formation from highly viscous fluids in a microfluidic T-junction have been investigated for different operating conditions. Both numerical and analytical models have been developed to predict the pressure characteristics during different stages of the droplet formulation, and comparison of results is presented. Further, an experimental investigation is performed for validating the present numerical model. Excellent agreement has been observed between the numerical and experimental results. The effects of wettability of the channel wall and a high viscosity ratio on pressure characteristics have been investigated. Pressure decreases with an increase in contact angle or hydrophobicity of the channel wall, whereas the frequency of the pressure fluctuation increases with an increase in contact angle. The amplitude of pressure fluctuation decreases with an increase in viscosity of the dispersed phase, while the frequency of the fluctuations increases. The frequency of the pressure fluctuation coincides with the frequency of the droplet formation. At a high capillary number, pressure is characterized by low amplitude and high frequency (LAHF) fluctuations, whereas at a low capillary number, pressure is characterized by high amplitude and low frequency (HALF) fluctuations.