Metformin use in the United States
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Trends in Metformin Prescribing in the United States
Metformin use in the United States has grown dramatically over the past two decades. From 2000 to 2015, the number of metformin prescriptions increased steadily, with an estimated 553 million prescriptions dispensed during this period. The rate of FDA-approved metformin prescriptions rose from 2.27 per 1,000 people in 2000 to 235 per 1,000 in 2015. Off-label use also increased, from 0.74 to 20.3 per 1,000 people. The most significant increases were seen in adults aged 50–64 and those over 65, but all age groups experienced growth in metformin use. Off-label prescribing was most common for endocrine, cardiovascular, female reproductive, and metabolic disorders .
Metformin Use in Prediabetes
Despite recommendations from the American Diabetes Association to consider metformin for adults with prediabetes and additional risk factors, actual use remains very low. Between 2005 and 2012, less than 1% of U.S. adults with prediabetes reported using metformin. Even among those with a BMI of 35 or higher, where guidelines specifically recommend metformin, usage was only slightly higher. Metformin use did not differ by race, income, or education level .
Metformin in Special Populations: Kidney Transplant Recipients and Chronic Disease
Metformin is generally contraindicated in patients with significant kidney dysfunction, but many kidney transplant recipients in the U.S. still receive it. These patients tend to have better kidney function before starting metformin, and its use was not linked to worse patient or allograft survival. In fact, metformin was associated with lower mortality and better allograft survival at three years post-transplant .
For patients with chronic kidney disease (CKD), congestive heart failure (CHF), or chronic liver disease (CLD), metformin was historically avoided due to concerns about lactic acidosis. However, recent evidence suggests that metformin is safe for many patients with moderate CKD or CHF, and the FDA has updated its guidelines to allow use in patients with an estimated glomerular filtration rate (eGFR) of 30–60 mL/min/1.73 m². As a result, more patients with these conditions are now eligible for metformin therapy .
Expanding Clinical Applications and Off-Label Use
Metformin’s use has expanded beyond type 2 diabetes. It is now prescribed for various conditions, including obesity, metabolic syndrome, cardiovascular disease, cancer, and even cognitive decline. Its potential benefits in non-diabetic populations are being explored, and it is sometimes used as part of combination therapies in cancer treatment . In pediatrics, metformin is used for type 2 diabetes and other conditions, with ongoing research into its broader applications in children .
Historical Context and First-Line Therapy Status
Metformin was introduced in the U.S. in 1995 and quickly became the preferred first-line oral medication for type 2 diabetes due to its effectiveness, safety, and low risk of weight gain or hypoglycemia. Long-term studies have shown cardiovascular benefits, further supporting its widespread adoption. Despite the introduction of newer diabetes medications with additional benefits for high-risk patients, metformin remains the recommended initial therapy for most people with type 2 diabetes, largely due to its affordability and established safety profile 78.
Conclusion
Metformin use in the United States has increased substantially, driven by its effectiveness, safety, and expanding indications. While its use in prediabetes remains limited, it is widely prescribed for type 2 diabetes and is increasingly used in populations with chronic diseases and in off-label scenarios. Ongoing research continues to explore its potential benefits beyond diabetes, ensuring metformin’s prominent role in U.S. clinical practice.
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