I don't know if there is an exact correct answer, but think about function and flow. For example, make sure that your refrigerator door can fully open without banging into the island!

Optimal flow is 48", but you can squeeze by with 42". For a through fare traffic pattern (major doorway to doorway) 60" is more comfortable, especially if a refrigerator is in the traffic pattern.

1200mm is ideal. Though it does depend on how many cooks use the kitchen