There are data on the beneficial effects of metformin on the recurrence, progression and survival of prostate cancer [15, 16]; however, large epidemiologic studies of metformin on BPH that adjust for sociodemographic factors and comorbid conditions are very limited despite the preclinical data that suggests metformin inhibits BPH progression by inhibiting insulin-like growth hormone 1 (IGF-1), which influences the proliferation of prostatic tissue and altered male hormone activity in the prostate [17, 18]. This evidence concerns the gene IGF1 and benign prostatic hyperplasia.