The centre back has been with Preston for several months after training with the club prior to the lifting of his suspension from football. He featured in and around the first team but it was clear that fitness was his main issue.
Lowe was impressed enough to offer a two year deal and Diaby will now compete for a spot at the back. This is a position Lowe was looking at given Van den Berg returned to Liverpool following his loan spell and Huntington leaving the club.
It will be interesting to see how Diaby fairs after a full pre-season under his belt. He will certainly offer a physical presence at the back and given Lowe likes to play three centre backs he has a chance of making an impact.