Saccharides stabilize proteins exposed to thermal fluctuations and stresses. While the effect of a layer of trehalose around a protein on the melting temperature has been well studied, its role as a thermal insulator remains unclear. We report calculations of thermalization in small saccharides, including glucose, galactose, lactose, and trehalose, and thermal transport through a trehalose layer between water and protein and between gold, such as a gold nanoparticle, and its cellular environment. The thermalization rates calculated for the saccharides provide information about the scope of applicability of approaches that can be used to predict thermal conduction in these systems, specifically where Fourier's law breaks down and where a Landauer approach is suitable. We find that trehalose serves as an excellent molecular insulator over a wide range of temperatures.