What is the evidence of increased cancer risk from insulin glargine (Lantus) treatment of type 1 diabetes mellitus (DM)?

Updated: Oct 08, 2021
  • Author: Romesh Khardori, MD, PhD, FACP; Chief Editor: George T Griffing, MD  more...
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Controversy has arisen over a disputed link between insulin glargine and cancer. On July 1, 2009, the FDA issued an early communication regarding a possible increased risk of cancer in patients using insulin glargine (Lantus). [150] The FDA communication was based on 4 observational studies that evaluated large patient databases and found some association between insulin glargine (and other insulin products) and various types of cancer.

The validity of the link remains in question, however. The duration of these observational studies was shorter than that considered necessary to evaluate for drug-related cancers. Additionally, findings were inconsistent within and across the studies, and patient characteristics differed across treatment groups.

In a study by Suissa et al, insulin glargine use was not associated with an increased risk of breast cancer during the first 5 years of use. The risk tended to increase after 5 years, however, and significantly so for the women who had taken other forms of insulin before starting insulin glargine. [151]

A study by Johnson et al found the same incidences for all cancers in patients receiving insulin glargine as in those not receiving insulin glargine. Overall, no increase in breast cancer rates was associated with insulin glargine use, although patients who used only insulin glargine had a higher rate of cancer than those who used another type of insulin. This finding was attributed to allocation bias and differences in baseline characteristics. [152]

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