Using Metadata API version 38.0 you can.
 
These lines downloaded the active version information for my flow:

    mConn = new MetadataPortTypeClient("SoapEndPoint", loginResult.metadataServerUrl);
    ...
    ...    
    readMetadataRequest r = new readMetadataRequest(metadataHeader, null, "FlowDefinition", new string[] { "ChangeProgressFlow" });
    readMetadataResponse rs = mConn.readMetadata(r);

If I fetch (**retrieve** package) the FlowDefinition for my flow, the XML is (**the same information I got using readMetadata**):

    <?xml version="1.0" encoding="UTF-8"?>
    <FlowDefinition xmlns="http://soap.sforce.com/2006/04/metadata">
        <activeVersionNumber>6</activeVersionNumber>
    </FlowDefinition>

My flow has 6 versions:

[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/wsw1x.png

I can fetch the content of each one but the active one (the first in the list).

If I try to get the XML of the active one, the error is: 

> Entity of type 'Flow' named 'ChangeProgressFlow' cannot be found

To get the content of the active one, my guess is that you have to append "**-VERSION**" to the name.