  P. Gabriel showed that for an unital ring $R$, there exists a bijective
correspondence between the set of Gabriel filters of $R$ and the set of Giraud
subcategories of $\mathrm{Mod}(R)$ (see \cite[Lemme 1]{Gabriel1} on page 412).
In this paper we prove analogous of Gabriel's result: for a small preadditive
category $\mathcal{C}$, there exists a bijective correspondence between the
Gabriel filters of $\mathcal{C}$ and Giraud subcategories of
$\mathrm{Mod}(\mathcal{C})$.
