NEW YORK (Reuters Health) - Smoking substantially raises the already elevated risk of heart disease among women with type 2 diabetes, study findings show.

But quitting, researchers report, can eventually cut their risk to that of diabetic women who never smoked.

Using data from a large, long-running US study of female nurses, Harvard investigators found that diabetic women who currently smoked 15 or more cigarettes a day had more than seven times the risk of heart disease compared with diabetic women who never smoked.

For those who were able to quit and remain abstinent for more than 10 years, however, the heart risk declined to the level of nonsmokers, Dr. Wael K. Al-Delaimy of the Harvard School of Public Health in Boston, Massachusetts, and colleagues report in the February 11th issue of Archives of Internal Medicine.

Type 2 diabetes occurs when the body can no longer properly use insulin, a hormone that helps shuttle sugar from the blood and into cells to be used for energy. The condition is closely associated with obesity and carries the risk of serious complications, including cardiovascular disease.

Smoking itself is a major contributor to heart disease and stroke, and experts believe that smoking may compound the diabetes-related problems--such as elevated cholesterol and susceptibility to blood-vessel blockage--that can lead to cardiovascular disease.

"Diabetic patients represent a high-risk population, and smoking is an added risk factor," Al-Delaimy told Reuters Health.

On the brighter side, the researcher noted, the extent to which long-term abstinence reversed study patients' added heart risk was surprising.

The investigators looked at data from the Nurses' Health Study, which has followed the health and lifestyle factors of close to 122,000 US women who were between the ages of 30 and 55 at the study's start in 1976. Over 20 years, more than 6,500 of the women developed type 2 diabetes, and 458 were diagnosed with heart disease.

Overall, the risk of heart disease rose in tandem with greater smoking. Among smokers, the heart disease rate was much higher among diabetics than nondiabetics. The risk of stroke was also elevated among current smokers.

And although women with diabetes were slightly less likely to smoke, other studies have found smoking to be as or more common among diabetics than in the general population--a fact the researchers call "alarming."

"Unfortunately," Al-Delaimy told Reuters Health, "many studies indicate that diabetic patients are not getting the warning about smoking from their healthcare providers that they should get."

SOURCE: Archives of Internal Medicine 2002;162:273-279.

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