Overcoming barriers to the use of metformin: patient and provider perspectives

Figures & data

Table 1 Motivations to use metformin

Source	Component theme	Exemplar quotation
Patient interviews/focus group
Reputation	Confidence in provider	“The fact that my doctor prescribed it, I think that’s the benefits right there”
	First-line drug	“Metformin is supposed to be the number one drug for type 2 diabetes”
Benefits	Glucose lowering	“It lowers my blood sugar or makes it normal on testing in the mornings” “My A1c has been fabulous”
	Other benefits	“When I first started taking metformin I lost about 50 pounds” “Anti-cancer benefits”
Provider
Reputation	First-line drug	“it’s really the first-line treatment” “I tell them what a great medication it is” “I am in love with metformin”
Safety		“There’s no question in my mind that it’s the safest of the medications that we have”
Benefits	Glucose lowering	“It’s the most effective”
	Weight loss Cost	“The next available drugs that cause weight loss with diabetes management are very much more costly”
Chart review
Benefits	General benefit	“Has metabolic syndrome so would support ongoing use of metformin despite goal A1c”
	Treating to HbA1c target	“Given increase HbA1c, may need to increase metformin dose”
No longer needed		“FINALLY OFF METFORMIN” “HbA1c 5.6 – normal – can stop metformin”

Table 2 Barriers to metformin use

Source	Component theme	Exemplar quotation
Patient
Side effects	Gastrointestinal side effects	“The one side effect that it gives me which is the runs”
	Other side effects	“He just put me back on metformin … one of my legs is starting to swell up again, like it used to”
	Absence	“Nothing that raises concerns, no side effects”
Provider
Side effects	Gastrointestinal side effects	“People complain about bloating and it just upsets their stomach. Some people get diarrhea”
	Other side effects	“A couple of women have complained of hair loss”
Chart review
Side effects	Gastrointestinal side effects	“did not tolerate metformin (GI issues)”
	Other side effects	“She stopped metformin because she was scared about losing her hair”
	Absence	“She is tolerating metformin without any side effects. ‘It’s like taking Chiclets’”
Reluctance	Nonspecific	“Pt does not want to take metformin”

Table 3 Strategies for improving metformin tolerance

Source	Component theme	Exemplar quotation
Patient
Adaptation	Toleration/lifestyle adaptation	“Sometimes it gives me diarrhea … I still wear [adult diapers] just in case”
	Timing around meals	“What I do is I take it about an hour and a half to two hours before I know that I’m actually going to sit down to have a full meal”.
Provider
Prescribing	Extended-release formulation	“I try generally to do the XR [extended release] to avoid diarrhea”
	Dose adjustment	“Start with a very low dose and then increase gradually”
Communication	Incentives	“I hold out the carrot of the weight loss”
	Timing around meals	“The people that I find do the worse are those who aren’t instructed how to take it. They’ll take it without food”.
Chart review
	Dose adjustment	“Restart [metformin] 500 mg daily and increase to BID as tolerated”
	Toleration	“On metformin with GI sx at first now completely resolved.”
		“Still feeling dizzy, feels no different off metformin x 2 weeks, her sx do not seem related to this med”

Table 4 Uncertainty, meaning lack of confidence or consistency, about key facts and effectiveness of interventions

Source	Component theme	Exemplar quotation
Provider
Prevalence	Varying answers to question “In your practice, how often do patients with diabetes stop metformin once they have started it?”*	“In our population, maybe half” “I would say 15% of the time” “5 to 10 percent. Maybe, probably close to 5%”
Side effects	Attribution of side effects	“Are they really having a side effect, or is it just there’s something that’s changed and it makes them feel very anxious?”
Effectiveness of interventions	Extended release formulation	“I don’t’ really know if there’s a correlation with side effects and sort of formulation, actually. I’m not sure”
	Dose adjustment	“I always start at 500 [mg]. But the times I’ve started at 1,000 [mg], I don’t necessarily think I’ve had a problem, interestingly”

Note: *In 9/10 interviews, the provider attributed the majority of such stoppages to gastrointestinal side effects in a subsequent question.

Table S1 Interview and focus group questions

Provider interview	Patient interview	Focus group
How often do patients with diabetes stop metformin once they have started it?	Would you say that you have (never taken metformin/used to take metformin/are currently taking metformin/not sure)	How do you think most people feel when they first get diagnosed with diabetes?
What are the most common reasons why patients stop taking metformin?	If you were prescribed metformin, what was it prescribed for?	Metformin is a prescription drug, often prescribed for people with type 2 diabetes. What have you heard about metformin?
If somebody has stopped taking it, how likely are you to attempt to put them back on metformin?	If you do take metformin, thinking about the last week, on how many days have you missed a dose of metformin?	When a person gets a prescription for metformin, what are some of the reasons they might want to take it?
Are there any methods you have found to help patients stay on metformin?	Have you had a good or bad experience on metformin? Why?	Some people (including may be some in this group) say that they stopped metformin at some point. What were some of the reasons people might stop taking metformin or might not want to take it in the first place?
Do you feel that it is a problem if patients with diabetes stop metformin?	Are there challenges or problems with taking metformin? If so, what are they?	If you were giving advice to doctors who help people with diabetes, what would you suggest that these doctors try to help their patients stay on metformin?
	Have you had any side effects from metformin?
	Are there benefits to taking metformin?