Patients diagnosed with cancer often skip the medications they’re taking for diabetes, although researchers aren’t sure exactly why.
It could be “life chaos” that comes with the diagnosis of, and treatment for, cancer, says a study in the February edition of Diabetologia. Medication adherence decreases during major life events when people are under stress.
A diagnosis of stage IV disease could be considered such a life event, say the authors, researchers at the Netherlands Comprehensive Cancer Organization and the University of Alberta. People with lethal cancers who take glucose-lowering drugs might understandably prioritize the fight against cancer over management of their diabetes.
The study tracked more than 16,000 patients with diabetes between 1998 and 2011. More than 3,200 of the patients were diagnosed with cancer.
The researchers gauged adherence by tracking the amount of glucose-lowering drugs patients with diabetes had in their possession over a certain period of time, or the medication possession ratio (MPR). A 10% decline in MPR, for example, means that a patient did not take a drug three days out of a 30-day month. In this study, a diagnosis of cancer resulted in a 6.3% drop in MPR at the time of the diagnosis.
The type of cancer influenced adherence. Those with prostate or breast cancer did not, for the most part, stop taking their glucose-lowering drugs. Patients diagnosed with more deadly cancers were more likely to stop. Those include cancers of the esophagus (19% decrease), lung (15.2% decrease), stomach, and pancreas (each about 10% decrease).
The MPR for patients with liver cancer declined 35%. The authors explain that liver cancer brings on diabetes and that it may resolve with tumor resection. In addition, metformin is contrandicated in people with advanced liver disease.