Basic Study
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Diabetes. Mar 15, 2021; 12(3): 261-277
Published online Mar 15, 2021. doi: 10.4239/wjd.v12.i3.261
Causal effect of education on type 2 diabetes: A network Mendelian randomization study
Li-Zhen Liao, Zhi-Chong Chen, Wei-Dong Li, Xiao-Dong Zhuang, Xin-Xue Liao
Li-Zhen Liao, Wei-Dong Li, Department ofHealth, Guangdong Pharmaceutical University, Guangzhou 510275, Guangdong Province, China
Li-Zhen Liao, Wei-Dong Li, Guangdong Provincial Key Laboratory of Pharmaceutical Bioactive Substances, Guangdong Pharmaceutical University, Guangzhou 510006, Guangdong Province, China
Zhi-Chong Chen, Department of Cardiology, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, Guangdong Province, China
Xiao-Dong Zhuang, Xin-Xue Liao, Department of Cardiology, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, Guangdong Province, China
Author contributions: Liao LZ and Chen ZC conceived the study and contributed equally to this study; Li WD completed the analyses; Zhuang XD led the writing; Liao XX supervised the study.
Supported by the National Natural Science Foundation of China, No. 81701378.
Institutional review board statement: Not applicable.
Conflict-of-interest statement: The authors declare that they have no conflict of interest to disclose.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Xin-Xue Liao, PhD, Chief Physician, Department of Cardiology, The First Affiliated Hospital of Sun Yat-Sen University, No. 58 Zhongshan 2nd Road, Yuexiu District, Guangzhou 510080, Guangdong Province, China.
Received: July 27, 2020
Peer-review started: July 27, 2020
First decision: November 4, 2020
Revised: November 10, 2020
Accepted: December 23, 2020
Article in press: December 23, 2020
Published online: March 15, 2021
Research background

The causality between education and type 2 diabetes mellitus (T2DM) remains unclear.

Research motivation

In this study, a network Mendelian randomization (MR) framework was applied to determine the causality between education and T2DM from summarized genome-wide association study data.

Research objectives

We used a network MR to identify the causality between education and T2DM and the potential metabolic risk factors [coronary heart disease (CHD), total cholesterol, low-density lipoprotein, triglycerides, body mass index (BMI), waist circumference (WC), waist-to-hip ratio, fasting insulin, fasting glucose, and glycated hemoglobin] from summarized genome-wide association study data.

Research methods

Two-sample MR and network MR were performed to obtain the causality between education-T2DM, education-mediator, and mediator-T2DM. Summary statistics from the Social Science Genetic Association Consortium (discovery data) and Neale Lab consortium (replication data) were used for education. DIAGRAM plus Metabochip consortium data were utilized for T2DM.

Research results

In the IVW method, the odds ratio (95%CI) for T2DM was 0.392 (0.263-0.583) per standard deviation increase (3.6 years) in education, without heterogeneity or horizontal pleiotropy. Education was genetically associated with CHD, triglycerides, BMI, WC, and waist-to-hip ratio in the discovery phase, yet only the results for CHD, BMI, and WC were confirmed in the replication data. Moreover, BMI was positively associated with T2DM.

Research conclusions

Short education was found to be associated with increased T2DM risk. BMI might serve as a potential mediator between them.

Research perspectives

For most developing countries, the majority of the population receive short education years. Longer education time is recommended as is a BMI control program, for public T2DM prevention.