TextRange.InsertBefore (PowerPoint)

Appends a string to the beginning of the specified text range. Returns a TextRange object that represents the appended text. When used without an argument, this method returns a zero-length string at the end of the specified range.

InsertBefore (NewText)

NewText: The text to be appended. The default value is an empty string.

Dim treInsertBefore As TextRange
Set treInsertBefore = ActivePresentation.Slides(1).Shapes(1).TextFrame.TextRange.InsertBefore()