The radial transport of suprathermal electrons caused by microturbulence is relevant both to the broadening of current and power deposition profiles driven by electron cyclotron and electron Bernstein waves [1] and to the confinement of runaway electrons, where turbulence-enhanced losses have been experimentally linked to electron-cyclotron heating power in TCV [2]. We present gyrokinetic calculations of the turbulent radial diffusion of suprathermal electrons in TCV-relevant plasmas. We show that even in low-beta conditions, the diffusion of fast electrons is dominated by electromagnetic fluctuations, consistent with longstanding theoretical expectations [3]. The resulting diffusion coefficients exhibit a highly nontrivial dependence on the velocity-space invariants (total momentum and magnetic moment), revealing novel features not captured by previous analyses. Two independent methods are employed to extract the diffusion coefficients. The first extends the approach of [1] by examining the particle flux of a trace electron species with Maxwellian equilibrium gradients, though this method is inherently limited by the non-Maxwellian nature of true suprathermal populations. The second method is novel: by removing the equilibrium distribution from the gyrokinetic equation, one recovers the continuum analogue of test-particle gyrocentre advection in turbulent electromagnetic fields. A passive distribution function, localised around a given flux surface, is evolved in time, and its radial spreading yields a diffusion coefficient directly. This approach is fully general and requires no assumption on the form of the equilibrium distribution, provided the transport is diffusive. Finally, we outline how a generalised relativistic gyrokinetic equation with an arbitrary equilibrium distribution function can be formulated to describe non-diffusive and pinch transport of suprathermal electrons in a more complete framework. [1] F.J. Casson et al., Nucl. Fusion 55, 012002 (2015) [2] J. Decker et al., Nucl. Fusion 64, 106027 (2024) [3] A.B. Rechester and M.N. Rosenbluth, Phys. Rev. Lett. 40, 38 (1978)