To investigate the effect of Dicer1 deficiency on diabetes development, we generated mice with a β-cell specific Dicer1 deletion from mid gestation (E9–11.5) using the Cre-lox system (RIP-Cre Dicer1Δ/Δ) by crossing RIP-Cre transgenic with Dicerflox/flox mice (Fig. 1A and B). This evidence concerns the gene DICER1 and diabetes mellitus.