Problem in extracting null value from a grid view field to add to a database table field

Hi,
I have a grid view and I am extracting a field value from the gridview corresponding to the chosen record via a radio button. Now for a particular record the field in grid view in asp.net is showing null value (blank). However when I am extracting this field value to add it to a database table the field in the table is populated by "&nbsp". I would like the field to be populated with null or even "". I am not sure how to do this.

The following approach is failing:

           If SelectedGridRow.Cells(5).Text = "&nbsp" Then
                SelectedGridRow.Cells(5).Text = ""
            Else
                Response.Write("Checking if statemen ...