We found that patients with DM on metformin, those with DM not on metformin and the control group of patients without DM had different molecular subtypes of BC: the luminal A subtype was found in 78%, 83% and 71%, the luminal B in 12.6%, 9% and 11%, HER-2 in 0.8%, 1.6% and 8%, and the triple-negative/basal-like subtype in 8.6%, 6.4% and 10%, respectively. Here, ERBB2 is linked to breast cancer.