Thanks for your answer, he is correct! Meanwhile I have found a solution with vba:
Sub Kreis_mit_r()
Dim s As Shape
Dim posX As Double, posY As Double
Set s = ActiveSelection.Shapes(1)
ActiveDocument.Unit = cdrMillimeter
'If s.Type = cdrCurveShape Then
'MsgBox "Kurvenlänge: " & vbCrLf & s.Curve.Length & " mm"
'End If
ActiveSelection.GetPosition posX, posY
ActiveDocument.Unit = cdrMillimeter
Set sh = ActiveLayer.CreateEllipse2(posX, posY, s.Curve.Length)
'sh.Outline.Color.GrayAssign 220
'ActiveDocument.Selection.Shapes(1).Fill.UniformColor.CMYKAssign 100, 0, 100, 0
End Sub
Thanks!