Metformin prescribing in low-income and insured patients with prediabetes.

Objectives: To describe prescribing patterns of metformin in low-income and Medicaid-insured patients with prediabetes and to identify common demographic characteristics and comorbid conditions of low-income and Medicaid-insured patients receiving metformin for treatment of prediabetes.

Design: Retrospective observational study.

Setting And Participants: Patients (18-60 years old) who were enrolled in South Carolina Medicaid and diagnosed with prediabetes between January 2009 and December 2013.

Main Outcome Measures: Metformin prescribing to treat prediabetes identified from pharmacy claims.

Results: Among 7102 patients who met the study criteria, 7.4% (n = 520) were prescribed metformin for prediabetes. Nearly 45% (n = 238) of eligible patients prescribed metformin initiated treatment within 30 days after diagnosis of prediabetes. Twenty-five percent of those prescribed metformin took 280 days or longer to initiate treatment after diagnosis of prediabetes. Older age, black race, managed care plan, comorbid hypertension and obesity, and longer enrollment period significantly increased the likelihood of metformin prescribing to treat prediabetes.

Conclusion: Prevalence of metformin prescription to treat prediabetes is less than 8% in low-income and Medicaid-insured patients. Sociodemographic characteristics and comorbid conditions influenced metformin prescribing in the low-income population.