Patients with diabetes mellitus are more likely to have diffuse CAD and microvascular disease. Current recommendation of invasive physiological assessment to guide percutaneous coronary intervention (PCI) is limited to FFR alone. This can be misleading in diffuse coronary artery disease and microvascular disease as both conditions are associated with higher FFR. The proportion of vessels which show discordance between FFR and CFR consistent with diffuse CAD and/or microvascular disease in patients has been shown to be as high as 30% in a study not exclusive to diabetics.