High count rate single photon detection at telecom wavelengths has been demonstrated using a thermoelectrically-cooled semiconductor diode. The device consists of a single InGaAs avalanche photodiode driven by a 2 GHz gating frequency signal and coupled to a tunable self-differencing circuit for enhanced detection sensitivity. The count rate is linear with the photon flux in the single photon detection regime over approximately four orders of magnitude, and saturates at 1 gigacount/s at high photon fluxes. This result highlights promising potential for APDs in high-bit-rate quantum information applications.