To assess whether initiation of insulin glargine (glargine), compared with initiation of neutral protamine Hagedorn (NPH) or insulin detemir (detemir), was associated with an increased risk of breast cancer in women with diabetes..
Ever use of glargine was not associated with an increased risk of breast cancer compared with NPH (HR 0.97; 95% CI 0.88–1.06) or detemir (HR, 0.98; 95% CI 0.92–1.05). No increased risk was seen with glargine use compared with either NPH or detemir by duration of insulin use, length of follow-up, or cumulative dose of insulin. No increased risk of breast cancer was observed in medium- or high-dose glargine users compared with low-dose users.
CONCLUSIONS Overall, glargine use was not associated with an increased risk of breast cancer compared with NPH or detemir in female Medicare beneficiaries