In stratified analyses by study design [7], [23], [24], [26]–[29], the odds of breast cancer was not elevated with insulin glargine use compared to non-glargine insulin use in observational studies (OR 1.02, 95% CI 0.68 to 1.53, P = 0.92; p for heterogeneity = 0.000, I2 = 83%). This evidence concerns the gene INS and breast cancer.