Inhibitory effect of metformin therapy on the incidence of colorectal advanced adenomas in patients with diabetes.
OBJECTIVE
Metformin use has been associated with decreased colorectal cancer risk and mortality among diabetic patients. Recent research suggests that metformin use may decrease the incidence of colorectal adenomas in diabetic patients with previous colorectal cancer. This study aimed to assess the clinical effect of metformin use on the development of colorectal adenomas in diabetic patients without previous colorectal cancer.


METHODS
Among 604 consecutive diabetic patients who underwent colonoscopic surveillance after initial colonoscopy between January 2002 and June 2012, 240 patients without previous colorectal cancer were enrolled in this study and were divided in two groups: 151 patients receiving metformin and 89 patients not receiving metformin. Patient demographics and clinical characteristics as well as the colorectal adenoma incidence rate were retrospectively analyzed.


RESULTS
The incidence rate of total colorectal adenomas was not different according to metformin use (P=0.349). However, the advanced adenoma incidence rate was significantly lower in the metformin group compared with the non-metformin group (relative risk [RR], 0.09; P=0.011). Metformin use was independently associated with a decreased incidence of advanced colorectal adenomas after adjustment for clinically relevant factors (RR, 0.072; P=0.016). In addition, the cumulative development rate of advanced adenomas during follow-up was significantly lower in the metformin group compared with the non-metformin group (P=0.007).


CONCLUSIONS
Metformin use in diabetic patients without previous colorectal cancer is associated with a lower risk of advanced colorectal adenomas.
Department of Internal Medicine, Dankook University College of Medicine, Choenan, Korea.
Yo Han
YH
Kim
Department of Internal Medicine, Dankook University College of Medicine, Choenan, Korea.
Ran
R
Noh
Department of Internal Medicine, Dankook University College of Medicine, Choenan, Korea.
Sun Young
SY
Cho
Department of Internal Medicine, Dankook University College of Medicine, Choenan, Korea.
Seong Jun
SJ
Park
Department of Internal Medicine, Dankook University College of Medicine, Choenan, Korea.
Soung Min
SM
Jeon
Department of Internal Medicine, Dankook University College of Medicine, Choenan, Korea.
Hyun Deok
HD
Shin
Department of Internal Medicine, Dankook University College of Medicine, Choenan, Korea.
Suk Bae
SB
Kim
Department of Internal Medicine, Dankook University College of Medicine, Choenan, Korea.
Jeong Eun
JE
Shin
Advanced colorectal adenoma; Diabetes mellitus; Incidence; Metformin