Smoking Linked to Diabetes
BIRMINGHAM, AL -- April 21, 2006 -- Smoking and exposure to passive or secondhand smoke may increase the risk of developing diabetes, according to a recent study (BMJ 2006 Apr 7). Among smokers, the risk of diabetes increased as the tobacco dose increased.
Researchers analyzed the CARDIA study (Coronary Artery Risk Development in Young Adults), a report on people in four large cities over a 15-year period. At the start of the study, the average age of the participants was 25 years. Half were African-American and half were Caucasian; 55% were women.
The 4,572 study participants included current smokers, ex-smokers, nonsmokers with no exposure to passive smoke, and individuals only exposed to passive smoke. Smoking activity was measured by questionnaires as well as by levels of cotinine, a breakdown product of nicotine that indicates exposure to smoke. Tobacco dose was measured by "pack years," or the number of cigarette packs smoked per day times the number of years that a person smoked.
Almost 17% of the subjects developed glucose intolerance or diabetes over the course of the study. The rate of glucose intolerance was highest among current smokers (21.8%), followed by nonsmokers who were exposed to passive smoke (17.2%), and then by former smokers (14.4%). The rate was lowest for nonsmokers who had never been exposed to passive smoke (11.5%).
Current smokers and nonsmokers exposed to passive smoke were 65% and 35% more likely, respectively, to develop diabetes than nonsmokers who had never been exposed to passive smoke. These calculations took into account health care access, eating patterns, economic status, sex, age, and race. Generally, white male smokers had the highest diabetes risk.
The researchers concluded that tobacco exposure is associated with the development of glucose intolerance over a 15 year period, with a dose-response effect. Previous studies link tobacco to chronic pancreatitis and cancer of the pancreas, suggesting that tobacco may directly injure the pancreas, they commented. Damage to the pancreas could then lead to glucose intolerance and diabetes.
Diabetes and Secondhand Smoke
The analysis of the CARDIA study may be the first report to identify passive tobacco exposure as a risk factor for glucose intolerance or diabetes, according to the study authors. "If confirmed by further research, these findings provide further documentation of the deleterious effects of tobacco smoking, and policy makers may use them as additional justification to reduce exposure to passive smoke," they said.
Secondhand smoke can also cause lung cancer, heart disease and respiratory problems including coughing, chest pain, reduced lung function, increased asthma attacks, and increased rates of pneumonia and bronchitis (American Cancer Society). For more information about secondhand smoke, and tips on how to quit smoking, see the CDC Tobacco Information and Prevention Source.