The popular diabetes medication Onglyza, which is a brand name for the generic drug saxagliptin, is used in combination with diet and exercise to help reduce high blood sugar levels in persons with type 2 diabetes.

Part of Onglyza’s appeal is that it allows diabetes patients to keep their blood sugar under control without causing the weight gain that is associated with some other diabetes medications.

Sales of the drug grew to $786 million in 2015, and some projections say they could exceed $2 billion by 2018.

Both Onglyza and another medication containing saxagliptin, Kombiglyze XR, are in a class of drugs called DPP-4 inhibitors. These drugs promote better control of blood sugar by triggering the pancreas to produce more insulin. They also direct the pancreas to produce less glucagon, a hormone that makes the liver produce more glucose.

These drugs are part of a larger class of medications known as incretin mimetics. Generally, these drugs work by promoting the function of incretin hormones to stimulate increased insulin production after meals. But while the scientific community hasn’t yet reached consensus on the issue, some research suggests that use of incretin mimetics could be one of the causes of thyroid cancer.

Possible Causes of Thyroid Cancer

Other incretin mimetics have been associated with cancer-related changes in the thyroid tissue of animal subjects. In human patients, dozens of cases of thyroid cancer have been reported among patients treated with other incretin mimetics. Among users of exenatide, 74 such cases have been reported, and 57 cases have been reported among users of liraglutide.

In an article published in the online journal Diabetes Care in May 2013, a group of doctors expressed concern that the medical community is responding to the possible cancer-causing effects of incretin mimetics in a typical and dangerous way.

Lead writer Dr. Peter C. Butler of UCLA described the pattern in which new diabetes medications can be rushed to the market without evidence of long-term beneficial outcomes. “Evidence of harm accumulates but is vigorously discounted,” Dr. Butler notes. “The regulators allow years to pass before they act. The manufacturers are expected – quite unrealistically – to monitor the safety of their own product.’’

Since Onglyza was first approved by the FDA only in 2009, researchers have not had a chance to fully evaluate the drug’s long-term side effects.

Other Cancer Connections to Onglyza

Drugs in the same class as Onglyza have also been connected with pre-cancerous changes elsewhere in the body. In March 2013, the FDA issued a Drug Safety Communication alerting physicians and patients to the results of recent studies that suggested a possible link between incretin mimetics like Onglyza and pre-cancerous cellular changes.

In those studies, researchers had found evidence of pancreatic duct metaplasia in type 2 diabetes patients who had been treated with incretin mimetics. Findings also suggested an increased risk of pancreatitis, which itself can be a precursor to cancer. The warning label for Onglyza has included a notice about the risk of pancreatitis since November 2011.