Researchers at the Jewish General Hospital's Lady Davis Institute for Medical Research in Montreal say oral corticosteroids have been known to increase the risk of diabetes -- more so with higher doses -- but this is the first time the effect has been observed in the inhaled form.
The study, published in the American Journal of Medicine, found inhaled corticosteroids increased the rate of onset of diabetes from 14 people per 1,000 to 19 per 1,000, or 34 percent, every year of use. In other words, 5 additional people for every 1,000 users in the study.
"These are not insubstantial numbers," lead author Dr. Samy Suissa said in a statement. "Over a large population the absolute numbers of affected people are significant. While the benefits clearly outweigh the risk for asthmatics, their effectiveness is questionable in COPD, where they are also used in higher doses. This is a very different risk/benefit situation."
Suissa and colleagues used the extensive databases of Quebec's provincial health insurance board to study nearly 400,000 patients treated for COPD or asthma.