New research has found that regularly smoking could increase the risk of developing type 2 diabetes in men, with the odds even higher in smokers who are also obese.
Carried out by researchers from the University of Oxford, UK, the Chinese Academy of Medical Sciences, and Peking University, the new study looked at 512,891 adults aged 30-79 years from five urban and five rural parts of China.
Participants had no history of diabetes at the start of the study, with the researchers following the health status of the participants for nine years using death and hospital admission records.
After taking into account factors such as age, socioeconomic status, alcohol consumption, physical activity and obesity, the team found that regular smokers have a 15-30 percent higher risk of developing diabetes compared with those who have never smoked.
Smoking more cigarettes each day and starting smoking at a younger age also appeared linked to a greater risk of diabetes.
The team also found that among men, being obese increased the risk of diabetes. Men who had a normal weight (a body mass index (BMI) of less that 25) and who smoked 30 cigarettes or more per day had a 30 percent higher risk of diabetes compared to those who didn’t smoke.
However, men who were obese (with a BMI of over 30) and smoked 30 cigarettes or more a day had a 60 percent higher risk.
Heavy smokers were also more likely to have higher amount of abdominal fat than light or non-smokers, which also greatly increased the risk of the condition.
Although smoking is much less common among women in China — only 3% of the study’s female participants regularly smoked, compared to 68% of the male participants — the risk of developing diabetes appeared to be even greater for female smokers than male smokers, possibly due in part to their greater proportion of body fat compared to men.
Although previous studies have suggested that giving up smoking may actually increase the risk of developing type 2 diabetes, at least in the short term, the team found that among ex-smokers this risk was only seen among recent quitters who had stopped smoking because of illness.
Among the individuals who had chosen to give up smoking, and who had stopped for more than 5 years, the researchers did find a small excess risk of diabetes but suggested that this could be due to moderate amount of weight gained following quitting.
Study author, Professor Liming Li, commented on the findings saying, “We can’t conclude from these findings that smoking causes type 2 diabetes, but, irrespective of this, smoking should be targeted as an important modifiable lifestyle factor in future disease prevention strategies, including for diabetes, in China and elsewhere.”
Co-author Dr. Fiona Bragg also added that “These findings add to existing evidence of the health benefits of giving up smoking, not only for prevention of cancer, respiratory and cardiovascular diseases, but now also for prevention of diabetes.”
The results can be found published online in The Lancet Public Health.