On has led to a so-called hyperinsulinemia hypothesis [11]; increased insulin level could promote colorectal tumor growth and act as a cell mitogen [12]. In support of this hypothesis, positive association between serum Cpeptide concentration and an increased colorectal cancer risk were found in several studies [13?5]. Although studies have reported a clear association of DM and hyperinsulinemia with the risk of colorectal cancer [16], association between DM and the risk of mortality in colorectal cancer patients is somewhat unclear. Historically, colon and rectal cancers have been considered together; however, the etiology and risk factors may differ among proximal colon, distal colon and rectal cancer. Indeed, several studies [17?0] have reported that DM was associated with the risk of proximal colon but not with distal and rectal cancers. Until now, most studies which evaluated the association between DM and the risk of mortality either included only colon cancer patientsSite Specific Effects of DM on Colorectal Cancer[21?4] or analyzed data from colon and rectal cancer patients together [25?7]. Very rarely, studies report the association between DM and the risk 
of mortality in rectal cancer patients separate from colon cancer. This could be due to relatively lower incidence of rectal cancer than colon cancer in Western countries [28], where most studies which investigated the association between DM and the risk of mortality in colorectal cancer patients were conducted. Furthermore, to our knowledge, the 
risk of mortality according to the site of colon cancer (proximal vs. distal colon) with and without DM has not been studied. Only one other study reported the association between DM and oncologic outcomes in an Asian population [23], important because the impact of DM on colorectal cancer outcomes could differ by race. With growing interest in and evidence of the relationship between DM and colorectal cancer outcomes, it is important to study the effects of DM on the risk of mortality according to the specific site of cancers in the colon and rectum in Asian population. Therefore, the purpose of this study is to investigate the impact of DM on oncologic outcomes in stage I-III colorectal cancer patients and to examine whether this association varies by the site of colorectal cancer (colon vs. rectum).was defined as the time from the date of surgery to death from any cause. Disease-free survival was defined as time from the date of surgery to tumor recurrence or occurrence of a new primary colorectal tumor or death from any cause. In addition, we defined recurrence-free survival as the time from the surgery to tumor recurrence or occurrence of a new primary colon tumor. For recurrence-free survival, patients who died without known tumor recurrence were censored. Colorectal specific-survival was defined as the time from the date of surgery to death from colorectal cancer-specific cause of death. In colorectal cancer-specific survival analyses, death as a result of other causes were censored. Patients were followed every three months 16574785 for the first two years after surgery, every 6 months in years 2?, then annually. Study outcomes were ascertained until October 31st 2011 through linkage to the hospital data base and the National Death Registry. Patients who remained alive at the end of the follow-up period were censored.Statistical AnalysisThe Kaplan-Meier method and log-rank test were used for overall survival, disease-free survival and.
