Diabetes can lead to shorter life

LOS ANGELES – A 50-year-old with Type 2 diabetes will lose an average six years of life as a result of the disease, only one year less than the seven that would be lost by a smoker of the same age, researchers reported Wednesday.

He or she is more than twice as likely to die of cardiovascular disease as someone without diabetes and 25 percent more likely to die of cancer, according to the report, an international study of more than 820,000 people published in the New England Journal of Medicine.

People with Type 2 diabetes are also more likely to die from kidney disease, liver disease, pneumonia, infectious diseases and even intentional self-harm, according to the study, which was conducted by the Emerging Risk Factors Collaboration, based at the University of Cambridge in England.

The data are especially concerning in light of the rapidly expanding incidence of diabetes in the United States, fueled by the growing spread of obesity. An estimated 25.8 million Americans now have diabetes, 10 million more than only two decades ago.

Researchers knew that diabetes could shorten life span, “but this really says how many years of life may be lost and to what causes,” said Dr. David M. Kendall, chief scientific and medical officer of the American Diabetes Association, who was not involved in the study.

The report also shows that those who have what is known as pre-diabetes – in which blood glucose levels are higher than normal, but not high enough to be classified as diabetic – are at risk from many of the same causes of death, he noted. An estimated 79 million Americans have pre-diabetes.

“Diabetes is often seen as a condition rather than an illness, something you can live with,” Kendall said. “Well, in fact, this shows that it is associated with a significant risk of both morbidity and mortality.”

The Emerging Risk Factors Collaboration is an international group of researchers that has previously studied the association of cholesterol, lipids and inflammation-promoting proteins in the blood with cardiovascular disease and other causes of death. In 2009, the group decided to extend the study to diabetes, focusing on 97 large studies that tracked subjects for an average of 13.5 years and had adequate information about fasting blood glucose levels, the diagnosis of diabetes and other medical conditions. None of the subjects had cardiovascular or other diseases at the beginning of the study.

The group reported that diabetics were 2.32 times as likely as nondiabetics to die from cardiovascular disease during the course of the study and 25 percent more likely to die from cancer. Diabetes was moderately associated with death from cancers of the liver, pancreas, ovary, colon and rectum, lung, bladder and breast. Diabetics were, however, less likely to die from prostate cancer.

Those findings are in general agreement with a recent statement issued jointly by the American Diabetes Association and the American Cancer Society. That document noted that it is unclear whether the cancers are caused directly by the high blood glucose levels or whether both diabetes and cancer are a result of underlying biological factors such as an inability of the body to properly respond to insulin or overproduction of insulin.

That document also noted there is not enough evidence about whether Type 1 diabetes, in which the pancreas stops producing insulin, is linked to an increased risk of cancer.

According to the new study, diabetics are also about three times as likely to die of kidney disease, 2.4 times as likely to die of infections (including pneumonia), 2.3 times as likely to die of liver disease, 70 percent more likely to die of falls, 64 percent more likely to die of mental disorders, 58 percent more likely to die of intentional self-harm and 27 percent more likely to die of chronic obstructive pulmonary disease.

“It’s surprising that everything under the sun was associated with diabetes,” said Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in New York, who was not involved in the research. It is clear why there is a link between diabetes and cardiovascular disease, he said, “but when it comes to nonvascular disease, it’s a little more difficult to understand why there is an association.”

For some of the causes of death, reduced immune function and impaired defense systems of the body are clearly playing a role, he added. But for others, “more studies are needed to somehow make these associations plausible.”