Metformin Associated with Less Need for a Second Medicine


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Am Fam Physician. 2015 Feb 15;91(4):261-262.

Clinical Question

How well do oral hypoglycemics treat type 2 diabetes mellitus without the addition of a second treatment?

Bottom Line

In this retrospective analysis, which benefits from large numbers of patients but suffers from possible biases, patients who initially took an oral hypoglycemic other than metformin (Glucophage) were significantly more likely to require a second oral agent. If prescribed a sulfonylurea, they were more likely to experience a cardiovascular event over the following year; if prescribed a thiazolidinedione or a dipeptidyl peptidase-4 inhibitor (gliptin), they incurred significantly more out-of-pocket cost of treatment. Despite guideline recommendations and good evidence of benefit, more than 40% of newly diagnosed patients were not prescribed metformin. (Level of Evidence = 2b)


This study evaluated a data set of one of the national health insurers in the United States. The researchers identified 15,516 patients who were started on a single oral hypoglycemic medicine. They analyzed subsequent prescriptions and hospitalizations for at least one year. Only 57.8% of patients received metformin as their initial therapy, which is recommended by most guidelines based on clear evidence of benefit. About one in four patients initially receiving metformin was eventually prescribed a second oral medicine, which was significantly less than those who started on a sulfonylurea (37.1%), a thiazolidinedione (39.6%), or a gliptin (36.2%). Patients started on a sulfonylurea were more likely than those taking other drugs to be subsequently started on insulin (9.1% vs. 5.1% to 6.2%). Patients started on a sulfonylurea were more likely to experience a cardiovascular event or a diagnosis of hypoglycemia. Patients initially prescribed a thiazolidenidione or a gliptin paid significantly more out of pocket.

Study design: Cohort (retrospective)

Funding source: Industry

Setting: Outpatient (any)

Reference: Berkowitz SA, Krumme AA, Avorn J, et al. Initial choice of oral glucose-lowering medication for diabetes mellitus: a patient-centered comparative effectiveness study. JAMA Intern Med.. 2014; 174( 12): 1955– 1962.

POEMs (patient-oriented evidence that matters) are provided by EssentialEvidence Plus, a point-of-care clinical decision support system published by Wiley-Blackwell. For more information, please see http://www.essentialevidenceplus.com. Copyright Wiley-Blackwell. Used with permission.

For definitions of levels of evidence used in POEMs, see http://www.essentialevidenceplus.com/product/ebm_loe.cfm?show=oxford.

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This series is coordinated by Sumi Sexton, MD, Associate Medical Editor.

A collection of POEMs published in AFP is available at http://www.aafp.org/afp/poems.


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