One in three people with diabetes prescribed metformin do not take the drug, new data reveals. Researchers believe this could be due to concerns over its side effects.
Scientists from the University of Surrey examined 1.6 million people with type 2 diabetes and how often they took prescribed medication. The data was extracted from 48 studies where oral and injectable therapies were compared.
Metformin is the most commonly prescribed type 2 diabetes drug, which helps to lower blood sugar levels, but it is known to have side effects including gut inflammation and nausea. Metformin SR (slow release) may be prescribed to people experiencing discomfort as a result of standard metformin.
Of those prescribed metformin, 30% did not take the required dosages, the highest percentage of noncompliance compared to other diabetes drugs such as sulphonyulreas (23%) and Actos (20%), a thiazolidinedione.
The drug class with the highest rate of adherence was DPP-4 inhibitors, a newer medication class, with only 10-20% of doses not taken.
When the study team compared injectable medications, patients were found to be twice as likely to cease GLP-1 agonist treatment compared with insulin.
Researchers believe that higher adherence to certain drugs is because of their minimal side effects, and hypothesise that multiple required doses per day could put people off adhering to treatment compared to once-daily medication.
Dr Andy McGover, Clinical Researcher at the University of Surrey, said: “The importance of diabetes patients taking their prescribed medication cannot be underestimated. A failure to do so can lead to complications in their condition including eye disease and kidney damage. Medication which is not taken does no good for the patient but still costs the NHS money so this is an important issue.
“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.”
The findings appear in the journal Diabetes, Obesity and Metabolism.

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