WEDNESDAY, Feb. 20 (HealthDay News) -- A staggering one in eight Americans has been diagnosed with type 2 diabetes, a new Harris Interactive/HealthDaypoll suggests.

And more than one third of those polled have been diagnosed with diabetes or have a parent, sibling, spouse or child with the condition.

"Type 2 diabetes has become one of the most common and fastest growing diseases. Fully one in eight adults -- approximately 29 million people -- now report that they have been diagnosed with this dangerous condition," said Harris Poll Chairman Humphrey Taylor.

Added Dr. Ronald Tamler, clinical director of the Mount Sinai Diabetes Center in New York City: "Diabetes is very insidious. You don't know you're in trouble until the complications hit or until it's so out of control you have uncontrolled urination and thirst" -- two of the common symptoms of diabetes.

While type 2 diabetes is occurring in epic proportions, the new poll also found that awareness of the disease is still surprisingly low, with only 21 percent of those surveyed considering themselves well-versed on the disease. That means the remaining 79 percent may not know they're at risk or may already have the disease, which is known as the "silent" killer.

But people already diagnosed with diabetes tend to be much more aware of the health risks, with slightly more than two-thirds considering themselves either "extremely" or "very" knowledgeable about the disease, the poll found.

Still, 35 percent of respondents with diabetes said their diabetes was only "somewhat" controlled and 5 percent said it was "not at all" well controlled.

"Because diabetes is a chronic condition, the treatment of which is critically dependent on patient behavior and self-care, this may be the most alarming finding," Taylor said.

On a more encouraging note, many people polled do understand that a number of factors can contribute to type 2 diabetes, including being overweight (79 percent of respondents realize this is a risk factor), diet (74 percent) and physical inactivity (62 percent).

These numbers were greater among people who had been diagnosed with diabetes.

Interestingly, 60 percent of respondents know that genetics can be a component of type 2 diabetes.

"We have a public perception that type 2 diabetes is entirely a disease of lifestyle and that is not true," said Dr. Robert Ratner, chief scientific and medical officer of the American Diabetes Association. "There is no question that lifestyle contributes to it, but the problem is one of biology . . . Environment really does play a role but the biology sets them up."

Indeed, certain ethnic groups, including many Native American tribes, bear a disproportionate diabetes burden, Ratner added.

Most adults, whether they actually have diabetes or not, seem fairly knowledgeable about the long-term consequences of the disease, which can include amputation of limbs, blindness, kidney disease and heart disease, the poll found.

There was an exception. Only 39 percent of adults overall and 56 percent of those with type 2 diabetes knew that the disease can cause strokes.

"People need to be aware that this is another disease caused by diabetes that can be prevented," said Nancy Copperman, director of Public Health Initiatives at North Shore-LIJ Health System in Great Neck, N.Y. "The idea of having a stroke might motivate them to change their lifestyle."

The disease seems to be taking a toll on those polled, with 20 percent acknowledging it has been a "significant" burden and 43 percent saying it has been "somewhat" of a burden for themselves and their families. The burden comes in the form of dietary restrictions, medication costs, eye problems, cardiovascular problems and foot problems.

In addition, 9 percent of people with type 2 diabetes said the condition has rendered them unable to work.

Still, with awareness of genetic factors as well as lifestyle contributors, "you can live a very full and happy life and thrive with diabetes," said Mount Sinai's Tamler.

In people with type 2 diabetes, either the body doesn't produce enough of the hormone insulin or cells can't use the insulin properly. Insulin is necessary for the body to use glucose -- blood sugar -- for energy. When glucose builds up in the blood instead of going into cells, it can lead to diabetes complications, according to the American Diabetes Association.

The prevalence of type 2 diabetes found in this new poll is higher than that reported by the U.S. Centers for Disease Control and Prevention, although the CDC data is more rigorous, Ratner said.

The poll was conducted online within the United States by Harris Interactive from Feb. 4 through 6, among 2,090 adults aged 18 and older. The survey was not based on a probability sample, so no estimate of theoretical sampling error can be calculated.

More information

Calculate your risk for diabetes at the American Diabetes Association.