Trial of an Intervention to Improve Metformin Persistence and Adherence
Status:
Completed
Trial end date:
2020-08-01
Target enrollment:
Participant gender:
Summary
Metformin is a safe and effective first-line drug for type 2 diabetes that is also widely
recommended for weight loss and diabetes prevention. But, metformin is associated with
gastrointestinal and other side effects which prevent its use in 10-20% of patients and
appear to limit the usable dose in others. This study is an N-of-1 trial design that will
recruit 20 previously metformin-intolerant patients for re-challenge with metformin in a
double-blind scenario. In this setting, 'intolerant' means either unable to take metformin at
all, or unable to increase the dose past 1,000 mg despite the treating physician's
recommendation to do so. Patients will be assigned to take their baseline medication regimen
plus 2 weeks of 250 mg per day of metformin extended release, followed by 500 mg metformin
XR, 750 mg, and 1,000 mg metformin XR with each treatment period separated by a 2-week course
of placebo. Initial treatment, placebo or metformin XR, will be decided randomly. At the end
of each two-week treatment period, participants will complete questionnaires assessing
overall satisfaction with the medication, gastrointestinal symptoms, and adherence. Six
months after the conclusion of the intervention, patients will be asked if they are
continuing metformin at a higher dose than upon entry to the trial. This trial has two aims.
First, to test the hypothesis that medication satisfaction will be the same during periods of
placebo treatment and during periods of treatment with the active drug. The second aim is to
test the hypothesis that > 30% of metformin-intolerant patients in an N of 1 crossover trial
are able to tolerate higher-dose metformin at 6-months.