糖尿病病人被新診斷罹患癌症之盛行率約為8 ~ 18%，糖尿病病人有意義地增加罹患所有型態及特殊位置癌症 (如：大腸直腸癌、乳癌、胃癌、胰臟癌、腎癌及前列腺癌) 風險。另有研究指出，降血糖藥物與糖尿病人癌症發生有關，其中研究最多的是metformin 有意義地減少肝細胞癌、大腸直腸癌、胰臟癌、胃癌、食道癌之發生，外源性胰島素 (exogenous insulin) 及磺醯尿素類 (sulfonylureas) 與增加乳癌、大腸直腸癌、胰臟癌、肝細胞癌有關，thiazolidinedione (TZD) 則與減少肝細胞癌有關。本文整理國際與臺灣地區糖尿病及癌症發生相關性研究結果，並回顧metformin 治療對癌症之影響。
 

Many systemic reviews and meta-analysis indicate that preexisting diabetes increased all types and sitespecific (e.g., colorectal, breast, gastric, pancreatic, renal and prostate) cancer incidences and mortalities. In addition, diabetes treatments were also related with either increased or reduced risks of cancer. Metformin showed a potential cancer protective effect significantly decreased hepatocellular carcinoma, colorectal,pancreatic, gastric and esophagus cancer for diabetic patients. However, exogenous insulin and sulfonylureas were associated with the risk of breast, colorectal, pancreatic cancers and hepatocellucar carcinoma.Thiazolidinediones were related with the decrease of hepatocellucar carcinoma. In this article, we review the association between cancer risk and diabetes and the evidence on the therapeutic effect of metformin.