Almost half of all adults with newly diagnosed type 2 diabetes who are prescribed the drug metformin stop taking it within a year — with the sharpest drop in use of the drug during the first 30 days, according to a new study published in the journal Diabetic Medicine.
Metformin is considered the first-line drug for type 2 diabetes, and is highly regarded for its efficacy at lowering blood glucose levels and for its low risk of adverse side effects. But about a third of people experience some digestive upset when they start taking the metformin, especially if they’re taking a higher dose of the drug (above 500 milligrams). In many people this side effect goes away or is greatly reduced over time, but if it continues, switching to an extended-release formulation of metformin may help relieve digestive discomfort.
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For the latest study, researchers looked at a group of people with newly diagnosed type 2 diabetes to study what drugs were prescribed, how well people stuck to taking drugs as prescribed, and how much these drugs cost. Out of 17,932 people with type 2 diagnosed between April 2012 and March 2017, 89% received a prescription for metformin as their initial drug treatment. Another 7.6% received a prescription for both metformin and another diabetes drug, while 3.3% were prescribed a different diabetes drug. People who started taking insulin as their first diabetes drug were excluded from the study, as noted in an article at Medscape.
Only 54% still filling metformin prescription after one year
Among all participants who were prescribed metformin, the available data showed that the proportion who filled their prescriptions to cover the prescribed number of days dropped by 10% after 30 days, by another 10% after 90 days, and again by 10% after 100 days. After one year, only 54% of people who were prescribed metformin still filled their prescriptions. Participants who continued to take metformin were more likely to be older, to have other health conditions in addition to diabetes, and to live in higher-income neighborhoods compared with those who stopped taking metformin.
When it came to health care costs, people who were originally prescribed a drug other than metformin had total health care costs that were about twice as high as those who were prescribed metformin by itself. This may be in part because people in this group were sicker for some reason, but an overwhelming factor is that their prescription drug costs were five to seven times higher than those of participants who took metformin (which is a low-cost generic drug). Factors that made participants more likely to account for higher health care costs included being younger, having a lower income, having a higher A1C level (a measure of long-term blood glucose control) at the time of their diabetes diagnosis, having other health conditions, and being male.
It’s unclear exactly why so many people stopped taking metformin, but part of the reason may be that many people with newly diagnosed type 2 diabetes don’t realize how important blood glucose control is, and they may feel just fine without taking the drug. If this is indeed the case — which would need to be confirmed by further survey-based studies — then the study’s results suggest that doctors may need to double down on emphasizing how important blood glucose control is to the long-term health of people with newly diagnosed diabetes. And if further researcher shows that the side effect of digestive upset plays a substantial role in people stopping metformin, then doctors may need to emphasize that there are plenty of options for changing the prescription of people who experience this problem.