PDO + MySQL always returns strings, but what about MsSQL?

PDO always returns field values as strings when using MySQL. Is PDO consistent when using another database like MSSQL?

If not, is there a flag which forces PDO to always return strings (for purpose of consistency)? or better still to return native types for all values?

From what I can tell, Drupal makes it possible to use different databases using PDO. It performs the necessary conversions to make SQL statements compatible with the varying syntaxes. But how does it deal with data types in query results?