The agency is to handle a campaign, the strategy for which is still being hammered out, promoting the diabetes brand to medics and consumers.
Associate director Nicola Brett leads a five-strong team on the account, which is Medicom's second major deal with Merck.
The agency already handles UK work for its cholesterol product Niaspan.
Medicom also worked on a Glucophage SR project last year, handling PR surrounding its presence at a Diabetes UK conference.
The agency won the new 2006 contract after a competitive pitch.
Glucophage SR has previously been promoted on a project basis by Trinity PR (PRWeek, 4 June 2004).
Type-2 diabetes is linked with weight problems. It usually occurs in people over the age of 40, but more children are reportedly being
diagnosed with the condition, some as young as seven years old.