Introduction: Patients with diabetes and familial hypercholesterolaemia (FH) are at very high risk of cardiovascular events, but rates of FH detection are very low in most countries, including Bulgaria. Given the lack of relevant data in the literature, we conducted a retrospective observational study to (1) identify individuals with previously undiagnosed FH among patients being treated at Bulgarian diabetes centres, and (2) gain insight into current management and attainment of low-density Enhanced Digital Features To view enhanced digital features for this article go to https://doi.org/10.6084/ m9.figshare.11342132.