Вы можете это событие, когда значение комбинированного списка было выбрано ...
Private Sub dataGridView_EditingControlShowing(ByVal sender As Object, ByVal e As DataGridViewEditingControlShowingEventArgs)
Try
If (Me.dataGridView.CurrentCell.ColumnIndex = CType(Column.Col,Integer)) Then
Dim comboBox As ComboBox = CType(e.Control,ComboBox)
If (Not (comboBox) Is Nothing) Then
AddHandler comboBox.SelectedIndexChanged, AddressOf Me.ComboBoxIndexChanged
End If
End If
Return
Catch Ex As Exception
Utils.ErrMsg(Ex.Message)
Return
End Try
End Sub