Does the use of insulin treatment for type 2 diabetes mellitus (DM) increase the risk of cancer?

Updated: Sep 27, 2021
  • Author: Romesh Khardori, MD, PhD, FACP; Chief Editor: George T Griffing, MD  more...
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On July 1, 2009, the FDA issued an early communication regarding a possible increased risk of cancer in patients using insulin glargine (Lantus). [273] 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.

Further evaluation is warranted, however, before the link between insulin use and cancer is confirmed. The duration of these observational studies was shorter than that considered to be 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. [274]

A study by Johnson et al found the same incidence rate for all cancers in patients receiving insulin glargine as in patients not receiving the drug. 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 did those who used another type of insulin. This finding was attributed to allocation bias and differences in baseline characteristics. [275]

A study by Steansdottir showed that different drug regimens used to accomplish intensified glycemic control did not alter the risk of cancer in patients with diabetes. [276] This study differs from previous studies, in which metformin use was associated with lower cancer risk.

The FDA states that patients should not stop taking insulin without consulting their physician. An ongoing review by the FDA will continue to update the medical community and consumers with additional information as it emerges. Statements from the ADA and the European Association for the Study of Diabetes called the findings conflicting and inconclusive and cautioned against overreaction.

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