Figure 3

Directed acyclic graph (DAG) of Mendelian randomization analysis using SNPs as instrumental variables (IVs). An IV satisfies three assumptions: (1) it is associated with BMI, i.e., there is an arrow from IV to BMI; (2) it is independent of confounders (both observed and unobserved), i.e., there is no arrow between IV and confounders; (3) it is independent of diabetes conditioning on BMI and confounders (known as no horizontal pleiotropy), i.e., there is no arrow between IV and diabetes. This last assumption, however can be relaxed, for example, in MR-Egger regression. A direct arrow from IV to diabetes is present in this figure because MR-Egger regression was included in our MR analysis.