Reports linking GlaxoSmithKline’s Avandia to increased cardiovascular risk, and the drug’s subsequent swoon, may prove just the tip of the iceberg for the diabetes field. Marketing research firm TNS says recent events will lead to more instability.

“The market upheaval is likely to continue and grow, as negative news hits about other diabetes drugs—such as the recent withdrawal of Exubera and concerns over Byetta’s potential link to acute pancreatitis,” said Philip O’Hagan, TNS Healthcare international client services director.

In the third quarter, after the media reports linking Avandia circulated, TNS saw a dramatic turnaround, with the majority of Avandia changes coming from doctors withdrawing patients from the drug. Potential cardiac issues drove 21% of those changes. That data point came from TNS’ DiabetesDynamics USA, a quarterly resource which tracks therapy changes and their causes in the type 2 diabetes market.