Now here's Meg Oliver with today's health watch report.Experts have crafted the first guidelines for millions who don't have diabetes yet, but are well on their way.The new game-plan emphasizes diet, exercise, and weight loss instead of medication.Lifestyle changes have been shown to be very successful in holding off the disease, but statistics have also shown far too few people try to do something about diabetes until it's too late.Teen smokers want to quit but often fail.More than 70-percent of teenagers in a new study indicated they wanted to stop but only 19-percent actually managed to quit smoking for at least 1 year.The numbers also show girls were more likely than boys both to want to quit and to succeed in doing so.Depression raises the danger of stroke in the elderly.Researchers studying the link found older people who were depressed had a nearly three-fold increased risk.Advocates hope the findings will push doctors to better diagnose and treat depression as a physical - and not just mental - condition.Those are some of today's top medical stories.I'm Meg Oliver - CBS News - New York