Sex hormone-binding globulin (SHBG) levels that are inversely associated with BC risk also suggest an IR role in BC development beyond age 55 since high SHBG levels are associated with enhanced insulin sensitivity, and low SHBG levels are associated with the development of type 2 diabetes mellitus (T2DM) in both men and women. The gene discussed is INS; the disease is type 2 diabetes mellitus.