The Millennium Stadium turned blue to mark World Diabetes Day, as figures show more than 153,000 people in Wales have been diagnosed with the condition.
The Cardiff stadium was lit by Diabetes UK Cymru as landmarks around the world, including Sydney Opera House, also went blue on Sunday.
The blue monument challenge is run by the International Diabetes Federation to keep the condition in the spotlight.
Some 7,000 people in Wales have been diagnosed in the past year alone.
A further 50,000 people are thought to have undiagnosed diabetes.
Wales rugby players including Matthew Rhys, James Hook and Shane Williams took time out from the autumn internationals to back the campaign.
Rees said: "As a squad and as individual players we are all very much aware of our responsibilities as role models to young children in Wales, and type two diabetes is a disease that can be directly related to a lack of exercise."
The theme of this year's World Diabetes Day was promoting physical activity.