The Deleterious Effect of Insulin Therapy:  A Possible Correlation With Increased Neoplasm Mortalities in the T2DM Population

Abstract

Background:  Diabetes mellitus (T2DM) is a significant health problem in the United States and throughout the world. Current treatment protocol advises weight reduction, healthy diet, and anti-diabetic medication as first-line therapy; however, many T2DM patients rapidly transition to an insulin regimen. Insulin is the most effective treatment in reducing blood glucose levels; however, it is associated with mitogenic effects. These effects, in addition to T2DM and its co-morbidities, may be responsible for a higher prevalence of mortality in those who develop malignancies.

Methods:  An exhaustive literature search utilizing Google Scholar, MEDLINE-Ovid, Web of Science, and CINAHL was conducted. The following search terms were used independently and in combination: neoplasm, mortality, cancer, insulin, and T2DM.  Reviewed studies were assessed for quality using GRADE.

Results:  Thirty-four articles were reviewed for relevancy. Three were included in this systematic review, designed as cohort studies, and demonstrated an increased rate in neoplasm mortality among insulin-treated type II diabetics. Of note, the Gu et al study found that the insulin therapy group experienced a significantly higher cancer mortality rate (fully adjusted RR=2.16, 95% CI 1.39–3.35, P=0.001) compared with non-insulin users. The third study also demonstrated a risk in that the insulin-treated cohort experienced greater cancer-related deaths than persons using metformin (1.9 (95% CI 1.5–2.4; P < 0.0001).

Conclusion:  Insulin treatment in T2DM may be associated with increased neoplasm mortalities. In the three observational cohort studies, insulin use has been associated with a higher prevalence of cancer death. Despite the evidence presented in this systemic review, further studies are recommended to confirm the data.

Keywords:  Neoplasm, mortality, cancer, insulin, type II diabetes mellitus

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REVIEWED STUDIES:

Bowker SL, Majumdar SR, Veugelers P, Johnson JA. Increased Cancer-Related Mortality for Patients With Type 2 Diabetes Who Use Sulfonylureas or Insulin. Diabetes Care. 2006;29(2):254-258.

Forssas E, Sund R, Manderbacka K, Arffman M, Ilanne-Parikka P, Keskimaki I. Increased cancer mortality in diabetic people treated with insulin: a register-based follow-up study. BMC Health Services Research. 2013;13:267.

Gu Y, Wang C, Zheng Y, Hou X, Mo Y, et al. Cancer Incidence and Mortality in Patients with Type 2 Diabetes Treated with Human Insulin: A Cohort Study in Shanghai. PLoS ONE. 2013;8(1): e53411. doi:10.1371/journal.pone.0053411

AUTHOR: Edmund Concepcion is currently completing his second year in the School of PA Studies at Pacific University, Oregon.  He will graduate with an MS degree in August 2017.