The diabetes drug metformin may also lower the risk of lung cancer – but only for those who don’t smoke.
Smokers, on the other hand, saw an increased risk of lung cancer while taking metformin, which helps control blood sugar levels in diabetes by suppressing the production of glucose by the liver.
“Our results suggest that risk might differ by smoking history. With metformin decreasing risk among nonsmokers and increasing risk among current smokers,” said Lori Sakoda, a research scientist at Kaiser Permanente Division of Research in Oakland, California.
The study included 47,351 diabetic patients 40 years of age and older who had included their smoking status in a health survey completed between 1994 and 1996.
During the 15 years of follow-up, 746 of those patients were diagnosed with lung cancer.
Those using metformin had a 31 percent lower risk of developing adenocarcinoma. The most common form of lung cancer in nonsmokers, if they had never smoked, while smokers using metformin had an 82 percent increased risk of developing small-cell carcinoma, a lung cancer commonly diagnosed in smokers.
The study appeared in the journal Cancer Prevention Research.