Incomplete spoiling of the transverse MRI signal causes errors in the T1 time estimated from variable flip angle measurements acquired with spoiled gradient-echo images. Diffusion spoiling is thought to lessen these effects. However, these conclusions are based on phantom experiments, using very long T2 times, or from in vivo simulation using infeasibly strong diffusion spoiling. Here we perform simulation and in vivo experiments to characterise the impact of diffusion spoiling in the short T2, low spoiling regime. We show that even under these conditions, diffusion spoiling reduces the dependence of the estimated T1 on both the phase-increment and the transmit field.