Dear Hao,
We recommend reading these two posts How to link data in DIABLO and Choosing Diablo Design Matrix.
You could consider first using a PLS or sparse PLS method on your two data sets before going to a DIABLO analysis. Also consider applying PLS-DA and sPLS-DA on each data set individually for a discriminant analysis. This will then help you understand the correlation structure (PLS) and discriminative power (PLS-DA) of you data before you move to DIABLO. See the bookdown vignette for some examples.
Kim-Anh