SFRP5 and diabetes mellitus: When the group of individuals with prediabetes/diabetes was subdivided into smaller groups of individuals with IFG, IGT, combined IFG/IGT, newly diagnosed type 2 diabetes and known type 2 diabetes, SFRP5 was inversely associated with the odds of IFG, IGT and known type 2 diabetes after full adjustment (Additional file 1: Table S2).