A major national health study of Latinos found that half of the participants between 45 and 64 years old were at high risk for diabetes. And one in three of those surveyed were unaware they had the chronic disease.

The National Institutes of Health released the results of the first phase of its ongoing study of Latino health at the University of Illinois at Chicago today. It is the largest health study of Latinos in the country and includes a random sample of more than 16,000 households in the Bronx, Chicago, Miami and San Diego, communities with significant Latino populations.

The epidemiological study collected information on five health areas: asthma, dental health, depression, diabetes and heart disease. Researchers in Chicago recruited 4,136 participants from seven city neighborhoods and gathered information about behavior, lifestyle choices and risk factors. The data was collected between 2008 and 2013.

“Latinos are the largest minority group in the U.S. and are often understudied and underserved,” said Dr. Martha Daviglus, director of the University of Illinois at Chicago’s Institute for Minority Health Research and principal investigator for the Chicago portion of the study. “We hope to provide better health education to the community and to help develop public policies that meet the needs of Latinos in the U.S.”

There are about 2.7 million Latinos in Chicago, or 29 percent of the population.

Dr. Bechara Choucair, commissioner of the city’s Department of Public Health, praised the study. Choucair said data is particularly important when making decisions about policy and resources.

“We don’t have a lot of resources,” he said. “We have to be thoughtful about how we use this data to implement programs.”

The city has used data effectively to target health disparity problems, he said. For example, data analysis showed that half of Latino youth smoked menthol-flavored cigarettes. Using this knowledge, Mayor Rahm Emanuel’s administration pushed to get City Council to restrict sales of flavored tobacco and restrict the sales of cigarettes near schools. City Council passed an ordinance which restricts both.

The second phase of the study started in June and will continue for another six years.

“We will be able to see how acculturation and lifestyle factors play a protective or detrimental role in the health of Hispanics,” Daviglus said.

The report also found that about 57 percent of Chicago participants age 18-64 lacked health insurance, trailing Miami, where 71 percent of participants were without coverage.

Other key findings of the national study include:

• Two out of three women ages 45-64 with diabetes had it under control.

• Women were more likely than men to know they had high blood pressure.

• About 40 percent of participants ages 18-44 were obese.

• On average, women age 45-64 spent only nine minutes each day in recreational physical activity.