Background: Statins are the cornerstone treatment for patients with heterozygous familial hypercholesterolaemia but research suggests it could increase the risk of type 2 diabetes in the general population. A low prevalence of type 2 diabetes was reported in some familial hypercholesterolaemia cohorts, raising the question of whether these patients are protected against type 2 diabetes. Obesity is a well known risk factor for the development of type 2 diabetes. We aimed to investigate the associations of known key determinants of type 2 diabetes with its prevalence in people with heterozygous familial hypercholesterolaemia., Methods: This worldwide cross-sectional study used individual-level data from the EAS FHSC registry and included adults older than 18 years with a clinical or genetic diagnosis of heterozygous familial hypercholesterolaemia who had data available on age, BMI, and diabetes status. Those with known or suspected homozygous familial hypercholesterolaemia and type 1 diabetes were excluded. The main outcome was prevalence of type 2 diabetes overall and by WHO region, and in relation to obesity (BMI ≥30·0 kg/m 2 ) and lipid-lowering medication as predictors. The study population was divided into 12 risk categories based on age (tertiles), obesity, and receiving statins, and the risk of type 2 diabetes was investigated using logistic regression., Findings: Among 46 683 adults with individual-level data in the FHSC registry, 24 784 with heterozygous familial hypercholesterolaemia were included in the analysis from 44 countries. 19 818 (80%) had a genetically confirmed diagnosis of heterozygous familial hypercholesterolaemia. Type 2 diabetes prevalence in the total population was 5·7% (1415 of 24 784), with 4·1% (817 of 19 818) in the genetically diagnosed cohort. Higher prevalence of type 2 diabetes was observed in the Eastern Mediterranean (58 [29·9%] of 194), South-East Asia and Western Pacific (214 [12·0%] of 1785), and the Americas (166 [8·5%] of 1955) than in Europe (excluding the Netherlands; 527 [8·0%] of 6579). Advancing age, a higher BMI category (obesity and overweight), and use of lipid-lowering medication were associated with a higher risk of type 2 diabetes, independent of sex and LDL cholesterol. Among the 12 risk categories, the probability of developing type 2 diabetes was higher in people in the highest risk category (aged 55-98 years, with obesity, and receiving statins; OR 74·42 [95% CI 47·04-117·73]) than in those in the lowest risk category (aged 18-38 years, without obesity, and not receiving statins). Those who did not have obesity, even if they were in the upper age tertile and receiving statins, had lower risk of type 2 diabetes (OR 24·42 [15·57-38·31]). The corresponding results in the genetically diagnosed cohort were OR 65·04 (40·67-104·02) for those with obesity in the highest risk category and OR 20·07 (12·73-31·65) for those without obesity., Interpretation: Adults with heterozygous familial hypercholesterolaemia in most WHO regions have a higher type 2 diabetes prevalence than in Europe. Obesity markedly increases the risk of diabetes associated with age and use of statins in these patients. Our results suggest that heterozygous familial hypercholesterolaemia does not protect against type 2 diabetes, hence managing obesity is essential to reduce type 2 diabetes in this patient population., Funding: Pfizer, Amgen, MSD, Sanofi-Aventis, Daiichi-Sankyo, and Regeneron., Competing Interests: Declaration of interests CAA-S reports support from Amgen to their institution. MAb reports support from Amryt for lectures and from Newbridge and Amryt to attend meetings. MAr reports grants to their institution from Novartis, Ionis, Lilly, and Amgen; and honoraria from Viatris, Alfasigma, Sanofi, Amgen, PIAM, Amaryn, Novartis, Ionis, and Ultragenyx. MAv reports consultancy fees from Akcea, Amgen, Amrith, Aurora Biofarma, Daiichi-Sankyo, Menarini, Novartis, Sanofi (Genzyme), and Sobi; and honoraria from Amgen, Amrith, Aurora Biofarma, Daiichi-Sankyo, Menarini, Novartis, Sanofi (Genzyme), and Sobi. FA reports support, consultancy fees, honoraria, and participation on a data safety monitoring or advisory board from Amgen, Amryt, and Novartis. RA reports honoraria from Amgen, Novo Nordisk, Tecnofarma, Saval, Abbott, and PTC-Therapeutics; support to attend meetings from Amgen And PTC-Therapeutics; participation on a data safety monitoring or advisory board for PTC-Therapeutics; and leadership or fiduciary, society, committee or advocacy group for Chilean Atherosclerosis Working Group. MBa reports participation at speakers bureaus for Amgen, Daiichi-Sankyo, Krka, Polpharma, Novartis, Sanofi-Aventis, Teva, and Zentiva; being a consultant for Adamed, Amgen, Daiichi-Sankyo, Esperion, New Amsterdam, Novartis, and Sanofi-Aventis; and grants from Amgen, Daiichi-Sankyo, Novartis, and Sanofi. CJB reports funding to the Austrian Familial Hypercholesterolaemia Registry from Amgen, Daiichi-Sankyo, Sanofi, and Novartis; consultancy fees from Novartis And Daiichi-Sankyo; and honoraria from Amgen and Novartis. MBo reports a grant to their institution from the Portuguese Science and Technology Foundation and Portuguese Cardiology Society. JB reports grants from AstraZeneca and honoraria from Amgen. LRB reports consultancy fees from Ultragenyx and Amryt; and honoraria from Amgen, HLS Therapeutics, and Novartis. ALC reports grants from Amryt, Menarini, and Ultragenyx; and honoraria from Amarin, Amgen, Amryt, AstraZeneca, Daiichi-Sankyo, Esperion, Ionis Pharmaceutical, Medscape, Menarini, Merck, Novartis, Novo Nordisk, PeerVoice, Pfizer, Recordati Regeneron, Sandoz, Sanofi, The Corpus, Ultragenyx, and Viatris. PC reports grants to FASTA University from Amgen; and consultancy fees and other honoraria from Amgen and Novartis. DC reports consultancy fees, including data safety monitoring, from Ultragenyx, Organon, and Novartis; honoraria from Bial, Alexion (Synageva), Daiichi-Sankyo, Amgen, Novartis, Organon, and Servier; support for attending meetings from Servier, Daiichi-Sankyo, and Medinfar; is the vice president of the Portuguese Atherosclerosis Society; and is a board member and ex-deputy director health of the Portuguese Society of Internal Medicine. OSD reports grants to their institution from Daiichi-Sankyo and Novartis; consultancy fees from Sanofi and Daiichi-Sankyo; and honoraria from Sanofi, Viatris, Organon, Daiichi-Sankyo, Novartis, and Servier. KID reports grants to their institution from Pfizer, Amgen, MSD, Sanofi-Aventis, Daiichi-Sankyo, and Regeneron; and personal fees from Bayer and Regeneron. AE reports grants to their institution from Regeneron, Daiichi-Sankyo, and Amgen. TF reports grants to their institution from Ministry of Education, Youth, and Sports, National Institute for Research of Metabolic and Cardiovascular Diseases Programme (EXCELES; LX22NPO5104) funded by Next Generation EU; and consultancy fees and other honoraria from Novartis. DG reports honoraria from Amgen, AstraZeneca, Boehringer Ingelheim, Novo Nordisk, Novartis, Pfizer, and Sanofi. UG reports grants from the Slovenian Research Agency and UMC Ljubljana Grant; honoraria from AstraZeneca and Novartis; and participation on a data safety monitoring board for Familial Hypercholesterolaemia Europe Foundation. KBH reports consultancy fees and other honoraria from Sanofi and participation in a scientific advisory board for Familial Hypercholesterolaemia Europe Foundation. GKH reports being a part-time employee of Novo Nordisk. MK reports honoraria for lectures and consultancy from Abbott, Abdi Ibrahim, Amryt, Novo Nordisk, and Tr-Pharma; funding from Amryt; participation in clinical trials with payments to their institution from Amgen, Ionis, Lib Therapeutics, Novo Nordisk, Sanofi, and Medpace; and participation in an unpaid advocacy group for Familial Hypercholesterolaemia-Türkiye and Familial Hypercholesterolaemia Europe Foundation. WK reports grants to their institution from Health Systems Research Institute; payments from Medical Council of Thailand, Royal College of Physicians of Thailand, Chulalongkorn University, Endocrine Society of Thailand, and Amgen; other honoraria from Amgen, Novartis, Boehringer, AstraZeneca, Abbot, and Thai Meiji; support to attend meetings from Amgen; and participation on an advisory board for Daiichi-Sankyo, Amgen, Kowa (Biopharm), Thai Meiji, Novartis, and Abbott. KL reports honoraria from Novartis, Novo Nordisk, AstraZeneca, and Boehringer. GL reports grants to their institution from Latvian Science Council (lzp-2020/1–0151), Latvian National Research Program Biomedicine for Public Health 2014–2017, the Ministry of Education and Science of the Republic of Latvia, and VPP-EM-BIOMEDICĪNA-2022/1–001 (State research project in the field of biomedicine, medical technologies and pharmacy); consultancy fees from Amgen, Novartis, Novo Nordisk, Boehringer Ingelheim, and Bayer; other honoraria from Pfizer, AstraZeneca, Servier, Sanofi, Novartis, Swixx BioPharma, Novo Nordisk, Boehringer Ingelheim, Bayer, Siemens Laboratories, Abbott Laboratories, and Roche Laboratories; support for attending meetings from Amgen, Bayer, Servier, and Sanofi; participation on data safety monitoring board for Amgen, Novartis, Novo Nordisk, Boehringer Ingelheim, and Bayer; and is a member of the certification council at the Latvian Medical Association Board, Latvian Society of Cardiology Board, and the Baltic Atherosclerosis Society. EL reports personal fees and non-financial support from Amgen, AstraZeneca, and Bayer; and personal fees from Servier, Boehringer Ingelheim, MSD, Lilly, Novartis, and Chiesi. ARML reports grants to their institution from Amgen, Daiichi-Sankyo, Regeneron, and Ultragenyx; and support for attending meetings from European Atherosclerosis Society. ADM reports grants from Medical Research Council Cape Heart Group; support to attend meetings from European Atherosclerosis Society; and is a board member and president of the Lipid and Atherosclerosis Society of Southern Africa. WM reports grants, consultancy fees, and other honoraria from Amgen, Sanofi, SYNLAB, Novartis, and Daiichi-Sankyo; and support to attend meetings from Daiichi-Sankyo. ARM reports grants from DiaGene Research Institute; grants and support to attend meetings from Sanofi and European Atherosclerosis Society; and is a president of Swiss Society for Familial Forms of Hypercholesterolemia. BGN reports consultancy fees from AstraZeneca, Sanofi, Regeneron, Ionis, Amgen, Kowa, Denka, Amarin, Novartis, Novo Nordisk, Esperion, Silence Therapeutics, and Ultragenyx; other honoraria from Sanofi, Kowa, Denka, Amarin, Novartis, Novo Nordisk, Abbott, and Mankind; board participation for Ionis, Kowa, and Novartis; and research collaboration with AstraZeneca. AGP is a board member of the Cyprus Atherosclerosis Society. FJR reports grants and personal fees from Amgen, Regeneron Pharmaceuticals, Novartis, and Lib Therapeutics. KKR reports grants to their institution from Amgen, Sanofi, Regeneron, Daiichi-Sankyo, and Ultragenyx; consultancy fees for serving as a member of the steering committee or executive committee of clinical trials and roles as principal investigator and national lead investigator and for attending advisory boards, providing advice on data interpretation, and future lines of research from Novartis, Daiichi-Sankyo, Kowa, Esperion, Novo Nordisk, MSD, Lilly, Silence Therapeutics, Az, New Amsterdam Pharma, Bayer, Beren Therapeutics, Cleerly, EmendoBio, Scribe, Crispr, Vaxxinity, Amarin, Regeneron, Ultragenyx, Cargene, and Resverlogix; lecture fees from Novartis, Bi, Az, Novo Nordisk, Viatris, Amarin, Biologix Pharma, Sanofi, Amgen, Esperion, Daiichi-Sankyo, Macleod Pharma for symposia at international meetings; holding stock options from New Amsterdam Pharma and Pemi31; and serving as a president for the European Atherosclerosis Society. ŽR reports grants from Sanofi Aventis and Novartis. RDS reports grants from Kowa, Amgen, Sanofi, Regeneron, Novartis, and Esperion; consultancy fees from Amgen, Novartis, Novo Nordisk, Amryt, Pfizer, Hypera, and Sanofi; and support to attend meetings from Novo Nordisk and Daiichi-Sankyo. HSc reports grants from AstraZeneca and consultancy fees from Amgen, AstraZeneca, Bayer Vital, Bristol Myers Squibb, MSD, Novartis, Servier, Sanofi-Aventis, Boehringer Ingelheim, Daiichi-Sankyo, and SYNLAB. CATS reports grants to their institution from Pfizer, Amgen, MSD, Sanofi Aventis, Daiichi-Sankyo, and Regeneron. MT reports grants, consultancy fees, other honoraria, support to attend meetings, and participation on an advisory board for Novartis. AJV-V reports grants to their institution from Pfizer, Amgen, MSD, Sanofi-Aventis, Daiichi-Sankyo, and Regeneron; consultancy fees from Bayer and Regeneron; other honoraria from Ferrer, European Atherosclerosis Society, and USA National Lipid Association; and support for attending meetings from the European Atherosclerosis Society, USA National Lipid Association, and Spanish Atherosclerosis Society. BV reports consultancy fees from Novartis, Amgen, Sanofi, and Zentiva; support to attend meetings from Zentiva; participates on a board for Novartis and Zentiva; and is the president of the Slovak Association of Atherosclerosis. LW reports grants from the National Key Research and Development Program of China and National Natural Science Foundation of China. GFW reports grants to their institution from Arrowhead Pharma, Amgen, Novartis, and Silence Therapeutics; consultancy fees from Amgen, Novartis, Sanofi, and Esperion; other honoraria from Amgen, Novartis, Sanofi, and Esperion; and support for attending meetings from Amgen, Novartis, Sanofi, and Esperion. ES reports consultancy fees to their institution from Amgen, Sanofi, Novo-Nordisk, Ionis, Merck, Novartis, and AstraZeneca. All other authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.)