Private Declare Function IsNTAdmin Lib "advpack.dll" (ByVal dwReserved As Long, _
  ByRef lpdwReserved As Long) As Long
 
Private Sub Command1_Click()
    If CBool(IsNTAdmin(0&, 0&)) Then
        MsgBox "User hat Admin-Rechte"
    Else
        MsgBox "User hat keine Admin-Rechte"
    End If
End Sub