There was an increased risk of breast cancer among overweight women compared with normal-weight women (crude HR 1.20, 95% CI 1.02–1.40), which remained significant after adjusting for age at menarche, use of HRT and oral contraceptives, age at first child birth, number of births, co-medications (insulin, metformin, and statins), heredity, and life-style factors (smoking and alcohol) (HRadj 1.19, 95% CI 1.01–1.40). This evidence concerns the gene INS and breast carcinoma.