BMI and DM: a two-sample mendelian randomization study

Introduction: Diabetes mellitus (DM) patients are often accompanied by an increase in BMI (body mass index). Obesity in clinical work is also often considered to be a high risk factor for diabetes, but whether there is a causal relationship between BMI and DM has not been clearly confirmed. Therefore, we conducted a two sample Mendelian randomization (MR) study to investigate the potential relationship. Method: We downloaded relevant data of "body mass index", "diabetes" and "type 2 diabetes (T2DM)" from the IEU OpenGWAS project database, used four different methods to conduct two sample MR analysis, and performed sensitivity analysis for verification. Results: The results of four MR analysis methods indicated that high BMI was indeed an independent risk factor for DM. Since T2DM was a main subtype of diabetes, we further analyzed the impact of BMI on T2DM and got the same results. The two OR values obtained through the IVW method in this study were: OR = 1.032 (95% CI, 1.014 to 1.051), P < 0.001 and OR = 1.005 (95% CI, 1.001 to 1.008), P = 0.011. Conclusion: Through our research, it was confirmed that high BMI was indeed an independent risk factor affecting the incidence rate of diabetes.