Type 2 diabetes mellitus is associated with cognitive decrements. Specifically affected cognitive domains are learning and memory, for which the hippocampus plays an essential role. The pathophysiological mechanism remains to be revealed. This study examined whether local hippocampal microstructure and white matter connectivity are related to type 2 diabetes and memory performance. Forty participants with type 2 diabetes and thirty-eight participants without type 2 diabetes underwent detailed cognitive assessment and 3-Tesla diffusion MRI. Diffusion MRI was performed to assess microstructure (fractional anisotropy and mean diffusivity) and white matter connectivity (tract volume) of the hippocampus, which were compared between participants with and without type 2 diabetes. No differences in hippocampal microstructure were observed. Participants with type 2 diabetes had fewer white matter connections between the hippocampus and frontal lobe (p=0.017). Participants who scored lower on memory function, regardless of type 2 diabetes, had fewer white matter connections between the hippocampus and temporal lobe (p=0.017). Taken together, type 2 diabetes and memory decrements appear to be associated with altered hippocampal white matter connectivity. This article is protected by copyright. All rights reserved.