Wenger hopes Diaby has the strength of character to overcome his latest injury setback after the France midfielder was ruled out for up to nine months with a serious knee injury.
After Saturday's 4-1 win against Reading, Wenger said: "That was the shock of the week for us, because I thought originally it was just a little twist of the knee.
"When they told me it was a rupture of his cruciate, and when you know what this guys has gone through, how many times he has worked day and night to come back in rehab, it is just demoralising.
"I hope he will find the resources and the strength to come back, because he was quite down.
"When you look at the number of problems he had, the surgeries, he is 26 years old and has had four or five big surgeries, that demands a lot of mental strength to come back, and I hope he will not give up and will continue."