Only one-third of American seniors with diabetes have their disease under control, a new study finds.

"This research gives us a good picture of diabetes control in older adults and gets us thinking about what it means that older Americans are not meeting clinical targets and how we should address this from a public health perspective," study leader Elizabeth Selvin, a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health in Baltimore, said in a school news release.

The study included almost 1,600 diabetes patients, aged 65 and older, in Maryland, Minnesota, Mississippi and North Carolina.

The researchers looked at whether the participants met American Diabetes Association guidelines for three key measures of good diabetes control: blood sugar, blood pressure and cholesterol levels.

The results showed that only one in three of the patients had diabetes controlled as defined by the ADA guidelines.

Some experts consider the ADA guidelines too demanding for seniors. But even using less stringent measures, the researchers found that many of the patients did not have their diabetes under control.

"There is tremendous debate about appropriate clinical targets for diabetes in older adults, particularly for glucose control. Are some older adults being over-treated? Are some being undertreated? These are questions for which we don't have answers," Selvin said.

The study also found significant racial disparities, particularly in women, in how well diabetes is managed.

Black women were much less likely than white women to have control of blood sugar, blood pressure and cholesterol levels, the researchers said.

The study appears in the July issue of the journal Diabetes Care.

One reason why seniors with diabetes may have more difficulty keeping their disease under control is that many of them have other health problems that may require more immediate attention from doctors, according to study co-author Christina Parrinello, who is also at the Johns Hopkins Bloomberg School of Public Health.

Parrinello noted that many of the complications associated with poor diabetes control take a long time to develop, possibly longer than the life expectancy of a patient with other illnesses.

Failure to keep diabetes under control increases the risk of long-term health problems such as nerve damage, blindness and kidney disease, the researchers noted.