A 50-year-old with diabetes dies six years sooner than someone without the disease, and not just from a heart attack or a stroke, new research suggests.
The large international effort to measure diabetes' toll found the disease also raises the risk of dying prematurely from a host of other ailments, even breast cancer and pneumonia.
"It's quite a wide sweep of conditions," said Dr. John Danesh of Cambridge University in Britain, who led the team of researchers. While most people think of heart problems, diabetes surprisingly "appears to be associated with a much broader range of health implications than previously suspected."
Putting the six years lost in context, he said, long-term smoking shortens life by 10 years.
The analysis used pooled medical information for 820,900 people from nearly 100 studies done mostly in Europe and North America. The results are published in Thursday's New England Journal of Medicine.
Diabetes, the seventh leading cause of death in the U.S., affects about 26 million Americans, or 8 percent, including 7 million who haven't been diagnosed. Most in the study were thought to have the most common kind - Type 2 - which occurs when the body makes too little insulin or cannot use what it does make to regulate blood sugar.
High blood sugar can damage nerves and blood vessels, and is a major cause of heart disease.
The new research didn't include those who had heart disease when they were first enrolled. Participants were followed on average for 13 1/2 years, and there more than 123,000 deaths. Overall, death rates from various causes were higher for those with diabetes than those without.
The researchers took into account other risk factors that could influence the results: age, gender, smoking and weight. Type 2 diabetes is tied to obesity. They found that those with diabetes had double the risk of dying from a heart attack or stroke, compared to those without the disorder. But they also found that diabetics had a 25 percent higher risk of dying from cancer and were more likely to die from a variety of illnesses including infections, lung and kidney disease as well as falls.
Exactly how diabetes raises those risks isn't clear, but in the case of infections, it could be that diabetes weakens the immune system, the researchers said. Diabetes can cause vision problems and loss of feeling in the legs, which may be the reason for falls, they said.
Danesh said one intriguing finding was a higher risk of suicide in those with diabetes. Other research has linked diabetes with depression, he noted.
The results are "another reason to try to normalize blood glucose in people who have diabetes," through diet, exercise and medication, said Dr. Alvin Powers, a diabetes specialist at Vanderbilt University. "There have been smaller studies that hinted at this but nothing where a study of this size looked at so many different outcomes."
Danesh and his colleagues also estimated diabetes' effect on life expectancy. They calculated that a 50-year-old diabetic without heart disease dies about six years earlier than someone without the disease, with 40 percent of the difference due to cancer and conditions other than heart disease.
"It underscores the need to prevent diabetes," Danesh said.
Previous studies have shown a possible link between diabetes and cancer. The new paper tied some, but not all, cancers; the increased risk ranged from 25 percent for breast cancer to double for liver cancer. Danesh said people with diabetes should get age-appropriate cancer screenings.
Last year, a joint report from the American Diabetes Association and the American Cancer Society looked at the issue and said that it wasn't clear whether any connection was direct, indirect or perhaps because the two disorders share common risk factors, like obesity.
The new research squares with that report's conclusion that "there's a lot more we need to understand about diabetes and the link to cancer," said one of the authors, Dr. Richard Bergenstal of the International Diabetes Center at Park Nicollet in Minneapolis. He a former president of the diabetes group.
While adding to the evidence, the study doesn't answer the question of why, he said.
"Diabetes is a serious condition. We often don't quite think about it quite that way," Bergenstal said.
Explore further: Pre-existing diabetes for persons diagnosed with cancer associated with increased risk of death
Diabetes information: http://www.diabetes.org and http://diabetes.niddk.nih.gov/
New England Journal of Medicine: http://www.nejm.org