One in Three Patients Skip Diabetes Medication Due to Side Effects

Type-2 diabetes patients most likely to pass on metformin

Diabetes patients who take the most commonly prescribed diabetes drug, metformin, are the least likely to follow medical advice regarding their medication due its side effects, an article in the journal Diabetes, Obesity and Metabolism reports.

Researchers from the University of Surrey in the United Kingdom examined in detail how likely 1.6 million people with type-2 diabetes were to take their medication. The study combined data from clinical trials and observational studies looking at adherence rates for both tablet and injectable medicines.

They found that those who took metformin, the most commonly prescribed drug to treat type-2 diabetes, were the least likely to take the required dosages compared to other diabetes drugs. Thirty percent of metformin doses prescribed to patients are not taken, compared to 23% of sulfonylureas (such as glimepiride) and 20% for pioglitazone.

Interestingly, dipeptidyl peptidase-4 (DPP4) inhibitors (gliptins), one of the newer medication classes, have the highest rates of adherence, with only 10% to 20% of medication doses not taken. When comparing injectable medications, it was found that patients are twice as likely to stop taking glucagon-like peptide-1 receptor agonists (such as exenatide) compared with insulin.

Researchers believe that the variance in adherence rates is in part due to side effects of the different drugs. Metformin commonly causes gastrointestinal symptoms such as diarrhea and flatulence, whereas DPP4 inhibitors are generally better tolerated by the body. It is also thought that having to take the multiple doses a day required for some drugs may have an impact on people taking the required medication.

"The importance of diabetes patients taking their prescribed medication cannot be underestimated,” said Dr. Andy McGovern, Clinical Researcher at the University of Surrey. “A failure to do so can lead to complications in their condition including eye disease and kidney damage.”

"We have known for a long time that a lot of medication prescribed for chronic diseases never actually get taken. What this latest research suggests is that patients find some of these medication classes much easier to take than others,” McGovern said. "Fortunately for type-2 diabetes we have lots of treatment options and switching to a different medication class which is easier to take could provide an easy way to improve adherence. I would also encourage doctors and nurses to actively ask their patients about medication adherence."

Data for this article was extracted from 48 studies, 25 of which compared oral therapies, 19 compared injectable therapies, three included comparison between oral and injectable therapies, and one which compared an oral to an inhaled agent.

Source: University of Surrey; December 17, 2017.