The U.S. Food and Drug Administration is warning that a drug used to treat diabetes may weaken bones and make them more susceptible to break.

Canagliflozin (Invokana, Invokamet) is an oral medication that helps people with Type 2 diabetes control blood sugar levels.

The FDA this week issued warning about the drug, saying that bone fractures had occurred in people taking it, some as soon as three months after starting on it. In addition, the drug has been linked to lower bone mineral density in the hip and spine, the regulators said.

The FDA approved the drug in 2013, but last year researchers at the National Institute of Diabetes and Digestive and Kidney diseases reported a possible relationship between the drug and bone fractures, especially for post-menopausal women.

The FDA based its warning an on nine studies of patients, who had on average taken the drug for nearly 20 months. In addition, a trial in 714 patients conducted as part of the drug’s postmarket evaluation found people taking it showed declines in bone density.

Already-known side effects of Invokana include dehydration, kidney problems, low blood sugar (when used with other diabetes medications), as well as high potassium levels in the blood, increased cholesterol, and yeast infections.