The prevalence of diabetes has increased almost 10-fold in China since the early 1980s, with one in 10 adults in China now affected by diabetes. Although adiposity is the major modifiable risk factor for diabetes, other research in China suggests this can explain only about 50% of the increase in diabetes prevalence over recent decades, suggesting other lifestyle factors, including smoking, may play a role in the aetiology of diabetes. In recent decades, there has been a large increase in cigarette smoking in China, especially among men. About two thirds of Chinese men now smoke, consuming roughly 40% of the world’s cigarettes.
Researchers from the University of Oxford, UK, the Chinese Academy of Medical Sciences and Peking University have examined the association of smoking and smoking cessation with the risk of diabetes in a large, nationwide study of 500,000 adults from 10 areas (five urban and five rural) of China. The present study included only people with no history of diabetes at the baseline, whose health status was monitored for nine years through death and hospital admission records. During this time over 13,500 participants developed new-onset type 2 diabetes.
The researchers found that, compared with people who have never smoked, regular smokers have a 15-30% higher risk of developing diabetes, after taking account of the effects of age, socioeconomic status, alcohol consumption, physical activity and adiposity. The study also showed a clear dose-response relationship with amount smoked and the earlier a person started smoking.
Among men, the smoking-associated risk of diabetes appeared to be greater among individuals with higher adiposity. Compared with those have who never smoked, smoking 30 cigarettes or more per day was associated with a 30% higher risk of diabetes among men with a normal weight (i.e. body mass index [BMI] <25 kg/m2) but with a 60% higher risk among men who were obese (i.e. with a BMI ≥30 kg/m2). Smokers, on average, tended to be leaner than non-smokers, possibly reflecting appetite suppression and elevated resting metabolic rate associated with smoking. However, heavy smokers were more likely to have higher abdominal adiposity than light or non-smokers, greatly increasing the risk of diabetes.
Read more at University of Oxford
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