The Associations of Hyperglycaemia and Insulin Usage with the Risk of Cancer in Type 2 Diabetes – the Hong Kong Diabetes Registry

  1. Juliana CN Chan, (MD, FRCP) (jchan{at}cuhk.edu.hk)1,2,3
  1. 1Department of Medicine and Therapeutics
  2. 2Hong Kong Institute of Diabetes and Obesity
  3. 3Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China

Abstract

Objective — Insulin has mitogenic effects while hyperglycaemia may be a risk factor for cancer in Type 2 diabetes mellitus (T2DM). It remains uncertain whether use of insulin increases cancer risk due to its effect on cell growth and proliferation or decrease cancer risk due to its glucose-lowering effect

Research Design and Methods — A 1:2 matched new insulin user cohort on age (+/−3 years), smoking status and likelihood of initiating insulin therapy (+/−0.05) was selected from a cohort of 4623 Chinese patients with T2DM, free of cancer and naïve to insulin at enrolment. Stratified Cox regression on the matched pairs was used to obtain hazard ratios (HRs) of insulin therapy and glycated hemoglobin (HbA1c) for cancer risk. A structured adjustment scheme was used to adjust for covariates.

Results — Out of 973 new insulin users, 971 had matched non users (n=1935). The cancer incidence in insulin non-users was much higher than that in insulin users (49.2 versus 10.2, per 1000 person-years, P<.0001). After further adjustment for all other covariates with a P value below 0.3 and non-linear associations with cancer, HbA1c was associated with an increased cancer risk (HR per %: 1.26, 95% CI: 1.03 to 1.55), while use of insulin was associated with a decreased cancer risk (HR of insulin users versus non-users: 0.17, 0.09 to 0.32). Consistent results were found in analyses including all 973 insulin users and 3650 nonusers.

Conclusions — In Chinese patients with T2DM, hyperglycaemia predicts cancer while insulin usage was associated with a reduced cancer risk.

Footnotes

    • Received September 15, 2009.
    • Accepted February 8, 2010.

This Article

  1. Diabetes
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