The health of Americans increased 1% this year, thanks to reductions in smoking, preventable hospitalizations and infectious disease, according to a health index sponsored by United Health Foundation (UHF).

But continued increases in obesity and children in poverty and a decline in Americans covered by health insurance largely offset healthy trends, according to UHF, a not-for-profit organization created by UnitedHealth Group Inc., Minnetonka, Minn. (NYSE:UNH).

The report, America’s Health Rankings, found 8.3% of American adults have diabetes. The percentage of adults who had been diagnosed with diabetes has risen 19% since 2005, according to the report, which UHF published jointly with the American Public Health Association and the Partnership for Prevention.

The rankings evaluate health, environmental and socio-economic data to establish national and state health levels. Data in the report came from the Centers for Disease Control and Prevention (CDC), American Medical Association, U.S. Department of Education, and the Census Bureau.

Vermont ranked as the healthiest state for the last four years, up from 17th in 1998. Massachusetts ranked second, up from third last year, followed in order by New Hampshire, Connecticut and Hawaii.

The study found obesity continued as one of the fastest-growing health problems in America, increasing 132% since 1990, from about 12% of the population to 27% in the 2010 study.

In the past year, smoking fell from 18.3% to 17.9% of U.S. adults, compared to a high of 29.5% in 1990. Utah, California, Massachusetts and Washington have smoking rates of less than 15%, UHF found.

The number of children in poverty increased from 17.4% in 2007 to 20.7% in 2010. UHF points out many of these children have limited access to health care and to healthy foods and opportunities for physical activity.

The percentage of Americans lacking health insurance coverage increased from 15.3% in 2009 to 16% in 2010 and has increased more than 2% since 2001, UHF found.

The report gives a number of examples of state success stories since the first edition of its rankings in 1990:

In that period, Maryland decreased the incidence of smoking from 29.7% to 15.1% of the population. Louisiana reduced the percentage of children in poverty from 38.5% to 19.5% of persons under age 18. Washington State decreased infant mortality from 9.7 to 4.8 deaths per 1,000 live births. Vermont decreased cardiovascular deaths from 401.7 to 241.1 per 100,000 population.

But despite spending more than any other country on health care, the U.S. falls behind other countries in a number of health measures. For instance, the U.S. lags 30 other countries in terms of a healthy life expectancy, with an average of 70 years. Japan leads all countries, with an expectancy of age 76.

The U.S. is also third to last in the rate of infant mortality among 37 developed nations, with seven deaths per 1,000 live births in 2008, compared to three deaths or fewer in Italy, Japan, Finland, France and Greece.

Out of 31 other industrialized countries, the U.S. ranks 29th in homicide rates, UHF reports.

-Trevor Thomas