To examine the diabetes-related gene expression in different breast cancer subtypes, we used a dataset with four differentiated breast cancer subtypes (ER+/PR+, ER+/PR−, ER−/PR+, and ER−/PR−) with 4032 patient tissue samples from the Breast Cancer Gene Expression Miner v4.5 [26,28]. The gene discussed is ESR1; the disease is breast cancer.