Insulin Glargine and Breast Cancer Risk: Is There a Connection?

Insulin glargine (glargine) use is likely not associated with an increased risk of breast cancer compared with the use of neutral protamine Hagedorn (NPH) or insulin detemir (detemir), according to new findings published in Diabetes Care.

Researchers arrived at this conclusion after performing a retrospective new user cohort study of female Medicare beneficiaries aged 65 years or older who had initiated glargine (n = 203,159), NPH (47,388), or detemir (n = 67,012) from September 2006 to September 2015. Follow-up occurred through May 2017.

Hazard ratios were estimated for incidence of breast cancer based on ever use, cumulative duration of use, cumulative insulin dose, length of follow-up time, and a combination of dose and length of follow-up time.

Results of the study indicated that ever use of glargine was not associated with an increased risk of breast cancer compared with NPH (HR 0.97) or detemir (HR 0.98). Furthermore, no increased breast cancer risk was observed with glargine use compared with either NPH or detemir based on duration of insulin use, length of follow-up, or cumulative dose of insulin.

Also of note, the researchers did not observe an increased risk of breast cancer in medium- or high-dose glargine users compared with low-dose users.

—Christina Vogt

Reference:
Bradley MC, Chillarige Y, Lee H, et al. Similar breast cancer risk in women older than 65 years initiating glargine, detemir, and NPH insulins. Diabetes Care. 2020;43(3). https://doi.org/10.2337/dc19-0614.