The association between leptin and subclinical cardiovascular disease explained by body fat: Observational and Mendelian randomization analyses

Background and aims: Leptin has been associated with adverse effects on cardiovascu-lar disease, but the effect of confounding by body fat in these associations remains unclear. To investigate associations between leptin and heart function and subclinical cardiovascular disease adjusted for total body fat, and to investigate the causal relation between leptin and cardiovas-cular disease using Mendelian randomisation.Methods and results: Leptin concentrations, total body fat and diverse measures of subclinical car-diovascular disease were determined in participants of the Netherlands Epidemiology of Obesity study. Linear regression between leptin concentration and measures of heart function, ECG mea-sures, and carotid intima media thickness as a measure of subclinical atherosclerosis was adjusted for potential confounding factors, and additionally including total body fat. We analysed the combined effects of genetic variants from a GWAS on leptin concentrations in publicly-available summary statistics of coronary heart disease GWAS (CARDIoGRAMplusC4D, n Z 184,305). As many as 6107 men and women, mean (SD) age 56 (6) years, BMI 26 (4) kg/ m2, and median leptin concentration 12.1 mg (IQR: 6.7-22.6) were included.In observational analyses, leptin was weakly associated with heart function and subclinical cardiovascular disease, but these associations attenuated when adjusting for total body fat. A doubling of genetically-determined leptin concentration was associated with an odds ratio of cardiovascular disease of 0.69 (0.37, 1.27).Conclusion: Observational associations between leptin and subclinical measures of cardiovascu-lar disease were largely explained by differences in total body fat. Results of analyses of genetically-determined leptin and coronary heart disease risk were inconclusive due to a large confidence interval. 2023 The Authors. Published by Elsevier B.V. on behalf of The Italian Diabetes Society, the Ital-ian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition and the Department of Clinical Medicine and Surgery, Federico II University. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).