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Insulin therapy and the risk of colorectal cancer in patients with type 2 diabetes: a meta‐analysis of observational studies
Author(s) -
Bu Wujie,
Song Lei,
Zhao Danyi,
Guo Bing,
Liu Jing
Publication year - 2014
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/bcp.12350
Subject(s) - medicine , relative risk , meta analysis , cohort study , colorectal cancer , confidence interval , type 2 diabetes , observational study , epidemiology , cochrane library , diabetes mellitus , cancer , endocrinology
Aims Several epidemiological studies have reported inconsistent associations between insulin therapy and the risk of colorectal cancer ( CRC ) in patients with type 2 diabetes mellitus. We performed this meta‐analysis of observational studies to evaluate the effect of insulin therapy on the risk of CRC . Methods We carried out a systematic search of P ub M ed, E mbase and the C ochrane L ibrary C entral database between J anuary 1966 and A ugust 2013. Fixed‐effects and random‐effects models were used to estimate the pooled relative risk ( RR ) and corresponding 95% confidence interval ( CI ). Results A total of 12 epidemiological studies were included in the present meta‐analysis, involving a total of 7947 CRC cases and 491 384 participants. There was significant heterogeneity among the studies, but no publication bias. Insulin therapy significantly increased the risk of CRC [ RR = 1.69, 95% CI (1.25, 2.27)]. When the various studies were stratified by study design, we found that insulin use was associated with a statistically significant 115% higher risk of CRC among case–control studies [ RR = 2.15, 95% CI (1.41, 3.26)], but not among cohort studies [ RR = 1.25, 95% CI (0.95, 1.65)]. Furthermore, a significant association was noted among studies conducted in USA [ RR = 1.73, 95% CI (1.15, 2.60)] and Asia [ RR = 2.55, 95% CI (2.14, 3.04)], but not in Europe [ RR = 1.20, 95% CI (0.92, 1.57)]. Conclusions The present meta‐analysis suggests that insulin therapy may increase the risk of CRC . More prospective cohort studies with longer follow‐up durations are warranted to confirm this association. Furthermore, future studies should report results stratified by gender and race and should adjust the results by more confounders.