Objective: Infant length (IL) is a positively associated phenotype of type 2 diabetes mellitus
(T2DM), but the causal relationship of which is still unclear. Here, we applied a Mendelian randomization
(MR) study to explore the causal relationship between IL and T2DM, which has the potential to
provide guidance for assessing T2DM activity and T2DM- prevention in young at-risk populations.
Materials and Methods: To classify the study, a two-sample MR, using genetic instrumental variables
(IVs) to explore the causal effect was applied to test the influence of IL on the risk of T2DM. In this
study, MR was carried out on GWAS data using 8 independent IL SNPs as IVs. The pooled odds ratio
(OR) of these SNPs was calculated by the inverse-variance weighted method for the assessment of the
risk the shorter IL brings to T2DM. Sensitivity validation was conducted to identify the effect of individual
SNPs. MR-Egger regression was used to detect pleiotropic bias of IVs.
Results: The pooled odds ratio from the IVW method was 1.03 (95% CI 0.89-1.18, P = 0.0785), low
intercept was -0.477, P = 0.252, and small fluctuation of ORs ranged from -0.062 ((0.966 - 1.03) /
1.03) to 0.05 ((1.081 - 1.03) / 1.03) in leave-one-out validation.
Conclusion: We validated that the shorter IL causes no additional risk to T2DM. The sensitivity analysis
and the MR-Egger regression analysis also provided adequate evidence that the above result was
not due to any heterogeneity or pleiotropic effect of IVs.