Caroline Evans, who published both titles, has left the company and Hachette has yet to replace her.
The company said it was reviewing the internal structure with regard to Sugar's publishing responsibilities. It could not confirm whether Evans had taken a new position elsewhere.
In the July to December ABCs, Sugar was ousted by Emap's Bliss as the UK's biggest-selling teenage magazine after posting a year-on-year circulation drop of 15.3%.
It subsequently changed to an A5 format and Hachette renewed the magazine's focus on new media. Evans had been working on a relaunch of Sugar's website and had begun talking to sales houses for exclusive online advertising content.
About 20 staff, including editor Nina Ahmad, accepted redundancies when B folded, but only two commercial positions were affected.
As well as Evans, ad manager Victoria Hennebury has also left to join The Daily Telegraph's magazine advertising team.