Write float nan (from C++ code) to sql server 2012

I am using following environment:
Database - Sql Server 2012
Language - C++11, Visual Studio 2015

I have a float, null parameter in a table in DB.
From my C++11 application, I want to write nan value to DB table as NULL.

I am doing following:
1. Converting nan to L"NULL" and store in CComBSTR
2. In DB, converting this string back to NULL and write this against float column.

My question: any better way of writing nan to DB in this case?
Specifically I want to avoid this CComBstr conversion as frequency of updates are quiet high and using many float parameters in table.