Metformin's Effects on Testosterone Levels in Women with PCOS

Mechanism of Action and Clinical Effects

Metformin improves insulin sensitivity, reducing insulin levels and subsequently decreasing ovarian androgen production, which contributes to lowering testosterone levels in women with PCOS, as noted by the American family physician 1
The medication tends to decrease weight in women with PCOS, unlike thiazolidinediones, which can lead to weight gain, and even modest weight loss enhances metformin's effects on metabolic and reproductive abnormalities 2

Even modest weight loss (5% of initial weight) improves both metabolic and reproductive abnormalities in PCOS, enhancing metformin's effects, according to the American family physician and supported by Practical Summaries of Clinical Guidelines from Praxis Medical Insights, though the latter is less preferred 2
The American College of Obstetricians and Gynecologists (ACOG) notes that interventions improving insulin sensitivity, including metformin, may positively impact risk factors for diabetes and cardiovascular disease in women with PCOS, a recommendation also supported by the Journal of the American College of Cardiology 1, 4

The American College of Cardiology recommends considering metformin particularly in women with PCOS who have cardiometabolic features such as abdominal obesity and insulin resistance, due to its potential to improve insulin sensitivity and reduce cardiovascular risk factors 4