Separating the direct effects of traits on atherosclerotic cardiovascular disease from those mediated by type 2 diabetes

• Published in: Diabetologia Vol. 65; no. 5; pp. 790 - 799
• Main Authors: Walker, Venexia M., Vujkovic, Marijana, Carter, Alice R., Davies, Neil M., Udler, Miriam S., Levin, Michael G., Davey Smith, George, Voight, Benjamin F., Gaunt, Tom R., Damrauer, Scott M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2022; Springer Nature B.V
• Subjects: Arteriosclerosis; Atherosclerosis; Cardiovascular disease; Cardiovascular Diseases; Coronary artery; Diabetes; Diabetes mellitus (non-insulin dependent); Diabetes Mellitus, Type 2; Fasting; Genome-Wide Association Study; Health risks; Heart diseases; Human Physiology; Humans; Insulin; Internal Medicine; Laboratory testing; Medicine; Medicine & Public Health; Mendelian Randomization Analysis; Metabolic Diseases; Peripheral Arterial Disease; Polymorphism, Single Nucleotide; Risk Factors; Vascular diseases; Vein & artery diseases; Type 2 diabetes; Direct effect; Atherosclerotic cardiovascular disease; Genome-wide association study; Indirect effect; Peripheral artery disease; Coronary artery disease; Mediation; Mendelian randomisation
• ISSN: 0012-186X; 1432-0428
• DOI: 10.1007/s00125-022-05653-1

Aims/hypothesis Type 2 diabetes and atherosclerotic CVD share many risk factors. This study aimed to systematically assess a broad range of continuous traits to separate their direct effects on coronary and peripheral artery disease from those mediated by type 2 diabetes. Methods Our main analysis was a two-step Mendelian randomisation for mediation to quantify the extent to which the associations observed between continuous traits and liability to atherosclerotic CVD were mediated by liability to type 2 diabetes. To support this analysis, we performed several univariate Mendelian randomisation analyses to examine the associations between our continuous traits, liability to type 2 diabetes and liability to atherosclerotic CVD. Results Eight traits were eligible for the two-step Mendelian randomisation with liability to coronary artery disease as the outcome and we found similar direct and total effects in most cases. Exceptions included fasting insulin and hip circumference where the proportion mediated by liability to type 2 diabetes was estimated as 56% and 52%, respectively. Six traits were eligible for the analysis with liability to peripheral artery disease as the outcome. Again, we found limited evidence to support mediation by liability to type 2 diabetes for all traits apart from fasting insulin (proportion mediated: 70%). Conclusions/interpretation Most traits were found to affect liability to atherosclerotic CVD independently of their relationship with liability to type 2 diabetes. These traits are therefore important for understanding atherosclerotic CVD risk regardless of an individual’s liability to type 2 diabetes. Graphical abstract