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 lipoprotein cholesterol (LDL-C) goals in such patients.From a database of diabetes centres across Bulgaria we retrieved medical records from patients aged ≥ 18 years with type 1/2 diabetes mellitus (T1DM/T2DM) who were being treated with insulin/insulin analogues, dipeptidyl peptidase 4 inhibitors, glucagon-like peptide 1 receptor agonists and/or sodium-glucose co-transporter-2 inhibitors. Patients with FH (Dutch Lipid Clinic Network score ≥ 3) were identified, and their data analyzed (lipid-modifying therapy (LMT), diabetes treatment, cardiovascular events and glycaemic and lipid parameters).A total of 450 diabetic patients with FH (92.0% with T2DM; 52.4% receiving insulin/insulin analogues) were included in the analysis. LMT consisted of statin monotherapy (86% of patients; 18% receiving high-intensity statin monotherapy), statin-based combination therapy (13%) or fenofibrate (< 1%). Median LDL-C was 4.4 mmol/L. Although 30% of patients had a glycated haemoglobin level of ≤ 7%, only one patient (< 1%) achieved the LDL-C target recommended in 2016 European guidelines for very high-risk patients (< 1.8 mmol/L). Previous cardiovascular events were documented in 40% of patients.To our knowledge, this is the first study to specifically explore lipid target achievement in diabetic patients with FH. In this preselected Bulgarian population, < 1% of patients achieved the 2016 European guideline-defined LDL-C target. These data highlight the importance of identifying FH in diabetic patients as early as possible so that they can receive appropriate treatment.