The Gunners have a very high opinion of the 19-year-old center back at present.
However, the Premier League side are not likely to secure him in January, given their limited spending power.
Per Record in Portugal, they are more likely to negotiate with Sporting for his signature in the summer.
Diomande is one who will be wanted by several top clubs around Europe in the coming months.
Arsenal will have to do a lot of work to ensure that he chooses North London as his next destination.