You haven't defined 'width' property on columns. Please define it or call 'fixColumnSize' method after inserting a new row.
$('#dg').datagrid('insertRow',{
index: 0,
row: {
itemid: 'Krueszack Lens',
productid: 30,
listprice: '132000',
unitcost: '200000',
attr1: 'None',
status: 'OK Go On, Long text Absolutely'
}
});
$('#dg').datagrid('fixColumnSize');
http://jsfiddle.net/tjf9jta9/1/