[plt-scheme] how to get GMT time?

I'd appreciate it if someone can tell me if this is the optimal way to
get a GMT time from Mzscheme:

(let ((offset (date-time-zone-offset (seconds->date (current-
seconds)))))
  (seconds->date (- (current-seconds) offset)))


It seems ugly to have to call date twice.  Also, can I count on the
time-zone-offset to always get me back to GMT, or do I also have
to consider whether it's daylight savings time?

Thanks, --pg