If you are adding rows to the last row in the DataGridView where the DataSource of the DataGridView is a DataTable you could setup a RowChanged event for the DataTable i.e.
Code:
AddHandler dt.RowChanged, AddressOf MyTable_RowChanged
Then access the fields i.e.
Code:
Private Sub MyTable_RowChanged( _
ByVal sender As Object, _
ByVal e As System.Data.DataRowChangeEventArgs) Handles MyTable.RowChanged
If e.Action = DataRowAction.Add Then
e.Row
End If
End Sub
From there save data access via e.Row to your database, get the ID and assign the ID to the new row.
If using MS-Access look at jmc's code bank submission for getting the new ID from an MS-Access table.
Any ways these are parts that should assist if adding rows via the DataGridView last row.