The ability to avoid overlapping of text objects created by the PIE function is not available in MATLAB. The problem occurs because there are two relatively small adjacent slivers (maybe < 2% of the total pie).
To work around this issue, you could use the EXPLODE syntax of PIE to push one of the adjacent slivers out a bit, thus separating their respective labels. The following pie chart avoids the overlapping labels:
pie([.1 .1 3 5 10],[1 0 0 0 0])
The logical vector represents which pie pieces to push out. You could identify this case and explode one of the pair of adjacent slices.