Most diabetics stop taking their glucose-lowering medications after they are diagnosed with cancer, according to a study published in the journal Diabetologia.
The study, conducted by researchers with the Netherlands Comprehensive Cancer Organization in Eindhoven, involved new users of type 2 diabetes drugs between 1998 and 2011 from the Eindhoven Cancer Registry-PHARMO Database Network. From that database, researchers examined 3,281 patients diagnosed with cancer and 12,891 who were not diagnosed with cancer during follow-up.
A medication possession ratio was used to determine drug adherence in both groups of patients. Researchers took note not only of cancer diagnosis, but also of specific cancer types. They found a significant drop in diabetes drug use when patients are first diagnosed with cancer. An ongoing but lower monthly decline of diabetes drug adherence was also observed after cancer diagnosis.
The decline in adherence in diabetic patients was observed for almost all cancer types, but was more pronounced in patients with esophageal, stomach, pulmonary, liver and pancreatic cancers.
Researchers said that adherence to glucose-lowering drugs may be especially beneficial to patients with the most severe or advanced types of cancer to help ward off complications such as hyperglycemia or ketoacidosis.
Diabetics are at greater risk of developing cancer compared to non-diabetics. Most require medication to help keep their blood sugar levels in control and ward off serious complications such as heart disease, kidney disease, neuropathy, dementia and blindness. But many diabetes treatments can actually increase one’s risk of developing cancer.
In 2011, studies linked the type 2 diabetes drug Actos to an increased risk of bladder cancer. Newer drugs Januvia and Byetta, in a popular class of medications known as incretin mimetics, increase the risk of acute pancreatitis and pancreatic cancer.
The question that remains on researchers’ minds is why many diabetic patients stop taking their glucose-lowering medications when they are diagnosed with cancer. “Is it the patient who prioritizes the fight against cancer or the advice of the physician to stop treatment?” researchers asked.