Insulin-like growth factor-I and insulin are associated with the presence and advancement of adenomatous polyps. Gastroenterology. 2005;129:464-475. [PMID: 16083703 DOI: 10.1053/j.gastro.2005.05.051]

Is Metformin Associated with a Lower Prevalence of Polyps, Adenomas, and Colorectal Carcinoma in Patients with Diabetes Mellitus?

PURPOSE

Recent studies suggested a protective role of metformin in the development of colorectal cancer (CRC) and its precursors. We aimed to investigate if metformin was associated with a lower prevalence and number of colorectal polyps in diabetic patients and also adenomas, high-risk adenomas, and CRC.

METHODS

Retrospective study on adult patients with diabetes mellitus followed in our hospital with a total colonoscopy between 2015 and 2019, treated with either metformin for > 5 years or other antidiabetic agent (control group). We assessed the number, size, and histopathology examination of proliferative lesions detected on colonoscopy.

RESULTS

We included 401 patients aged 69 ± 9 years, 57% males, divided into two groups: treated with metformin (n = 260) and without (n = 141). The number of polyps detected was significantly lower in patients under metformin (p = 0.014). There was a nonsignificant trend towards lower polyp detection rates in the metformin compared to the control group both in unadjusted analysis (50% vs 60%, p = 0.058) and multivariable adjusted analysis (odds ratio [OR] 0.68, 95% confidence interval [CI] 0.43-1.09, p = 0.111). In the latter, we identified male gender (OR 2.24, 95%CI 1.44-3.49, p < 0.001), age (OR 1.35 for every 10 years, 95%CI 1.07-1.71, p = 0.012), glycated hemoglobin value (OR 1.20 for every 1% increase, 95%CI 1.06-1.37, p = 0.005), and hypertension (OR 1.76, 95%CI 1.01-3.08, p = 0.046) as factors associated with a higher prevalence of polyps. We saw no statistically significant differences regarding adenoma (p = 0.231), high-risk adenoma (p = 0.810), and CRC (p = 0.705) diagnoses between groups.

CONCLUSION

In our study, metformin was associated with less colorectal polyps in diabetic patients compared to other treatment modalities. We observed a nonsignificant trend towards lower polyp detection rates in the metformin group both in unadjusted and adjusted analyses.

Association between diabetes mellitus and chronic rhinosinusitis with nasal polyps: A population-based cross-sectional study

OBJECTIVE

To investigate the association between physician-diagnosed diabetes mellitus (DM) and chronic rhinosinusitis (CRS) phenotypes in a national population-based study.

STUDY DESIGN

Retrospective cross-sectional study.

SETTING

Population-based survey data were collected by the Korean National Health and Nutrition Survey between January 2008 and December 2012.

PARTICIPANTS AND METHODS

A total of 34 670 participants aged over 19 years were enrolled in the Korea National Health and Nutrition Examination Surveys from 2008 to 2012. The relationship of CRS prevalence, with and without nasal polyps, with physician-diagnosed DM and non-DM were assessed. Differences in sinonasal symptoms between patients with and without DM were analysed in this cross-sectional study.

RESULTS

A significant association was observed between DM and CRS with nasal polyps after adjustment for multiple variables. No substantial association was observed between DM and CRS without nasal polyps. Among patients with CRS, olfactory dysfunction for >3 months was significantly more frequent in the DM group than in the non-DM group.

CONCLUSION

We demonstrated significant associations between DM and CRS with nasal polyps and olfactory dysfunction among patients with CRS in a large national clinical cohort study. The direct mechanism of the association between DM and CRS with nasal polyps should be further investigated to clarify the pathogenesis of CRS with nasal polyps.

Effect of Insulin and Metformin Combination Treatment on Colon Adenoma and Advanced Adenoma Among DM II

BACKGROUND

The risk for colorectal adenoma and advanced adenoma among diabetes mellitus II (DM II) has been debated to differ with the type of anti-diabetic therapy. Insulin increases whereas metformin decreases the risk for colon adenoma (Ad) and advanced Ad (AAd). There have been no studies to evaluate the effect of combination treatment with insulin and metformin on colon Ad and AAd.

METHODS

The retrospective study included DM II patients undergoing screening colonoscopy. Subjects with incomplete colonoscopy, poor bowel preparation, personal history of colorectal cancer (CRC)/inflammatory bowel disease/hereditary nonpolyposis colorectal cancer/familial adenomatosis polyposis/colectomy or family history of CRC were excluded. Subjects were categorized into group 1 (insulin only), group 2 (metformin only), group 3 (combination of insulin and metformin) and group 4 (miscellaneous). Group 4 was excluded from data analysis. Ad detection rate (ADR) and advanced ADR (AADR) were calculated for each group.

RESULTS

Three hundred thirty-nine subjects composed the study group, with a mean age of 60.0 years and male to female ratio of 1:1.4. Composite ADR and AADR for study population was 35.1 and 15.3 %, respectively. Groups 1, 2 and 3 were composed of 88 (26.0 %), 211 (62.2 %) and 40 (11.8 %) subjects, respectively. ADR for groups 1, 2 and 3 was 40.9, 33.2 and 32.5 %, respectively (p value = 0.413). AADR for groups 1, 2 and 3 was 18.2, 15.2 and 10.0 %, respectively (p value = 0.489).

CONCLUSION

A decremental trend was observed in ADR and AADR across group 1, group 2 and group 3 (p value >0.05).

Diabetes mellitus increases risk for colorectal adenomas in younger patients

AIM

To determine if diabetes mellitus (DM) is associated with increased risk of colorectal adenomas in younger subjects.

METHODS

This was a retrospective cohort study of 375 patients undergoing index colonoscopy at a single tertiary care center in the United States. Three cohorts of patients matched for exam date and gender were compared: (1) ages 40-49 years with DM; (2) ages 40-49 years without DM; and (3) ages 50-59 years without DM. Data collected included demographics, co-morbidities, colonoscopy and pathology results. Adenoma detection rates (ADR) were calculated and compared. Conditional logistic regression analysis was performed to determine the association between each cohort and ADR.

RESULTS

One hundred and twenty-five patients ages 40-49 with DM met study eligibility criteria. Patients in the other two cohorts were randomly selected, matching for date of exam and gender. ADR was 14.4% in those ages 40-49 years without DM, 30.4% in those ages 40-49 years with DM, and 32.0% in those ages 50-59 years without DM. Compared to those ages 40-49 years without DM, ADR was higher in those ages 40-49 years with DM (OR = 3.1; 95%CI: 1.5-6.4; P = 0.002) and those ages 50-59 years without DM (OR = 2.9; 95%CI: 1.5-5.6; P = 0.002). There was no difference between the ADR in those ages 40-49 years with DM and those ages 50-59 years without DM (P = 0.83).

CONCLUSION

DM was associated with higher risk of colorectal adenomas in patients ages 40-49 years. These subjects harbored as many adenomas as those at the standard screening age of 50-59 years without DM.

The association between obesity and colorectal adenoma: systematic review and meta-analysis

OBJECTIVE

Obesity (body mass index [BMI] ≥30) or overweight (25 ≤ BMI ≤29.9) has been reported to be a risk factor for colorectal adenoma (CRA). However, this association remains controversial. The aim of this study was to determine the association between overweight or obesity and CRA.

DESIGN

Systematic review and meta-analysis were conducted using English language studies from EMBASE and MEDLINE. Appropriate observational studies were selected from 1966 through September 2011. Adjusted odds ratios (ORs) were extracted from each study.

RESULTS

One hundred and seventy full-text articles were reviewed after retrieving 1199 initial search results. Five studies in which BMI was treated as continuous variable, three studies in which BMI was dichotomized using a cutoff value of 25, three studies in which BMI was categorized into three groups using values of 22 and 25, and eight studies in which BMI was categorized into three groups using values of 25 and 30 were selected. Regarding risk for CRA, pooled OR [95% CI] of one increment increase in BMI was 1.02 [0.99-1.03] (random effects model [REM]), while that of BMI ≥ 25 was 1.27 [1.15-1.4] (Fixed effects model). Pooled ORs [95% CI] of BMI ≥ 22 and BMI ≥ 25 was 1.42 [0.69-2.9] [REM] and 1.81 [0.36-9.1] [REM], respectively. Pooled ORs [95% CI] of BMI ≥ 25 and BMI ≥ 30 was 1.16 [0.98-1.38] [REM] and 1.47 [1.18-1.83] [REM], respectively.

CONCLUSION

Obesity and overweight are significant risk factors for CRA. However, there are no data showing linear relationship between increasing BMI and CRA.

Effects of omega-3 and omega-6 fatty acids on IGF-I receptor signalling in colorectal cancer cells

The insulin-like growth factor (IGF) system plays a critical role in normal growth and development as well as in malignant states. Most of the biological activities of the IGFs are mediated by the IGF-IR, which is over-expressed in most tumours and cancer cell lines. Fatty acids have critical roles in both systemic physiological processes (e.g. metabolism) and cellular events (e.g. proliferation, apoptosis, signal transduction, and gene expression). Alpha-linolenic acid (ALA) and linoleic acid (LA) are essential fatty acids of the omega-3 and omega-6 families, respectively. The aim of this study was to investigate the potential interactions between fatty acids and the IGF signal transduction pathways, and to evaluate the impact of this interplay on colon cancer cells survival and proliferation. Results of Western blot analyses revealed that ALA and LA enhanced the ligand-induced IGF-IR phosphorylation and, in addition, increased receptor phosphorylation in an IGF-I independent manner. Furthermore, fatty acid treatment led to phosphorylation of downstream signalling molecules, including Akt and Erk. In addition, FACS analysis and apoptosis measurements indicated that ALA and LA have a potential mitogenic effect on HCT116 cells, as reflected by the number of cells in S phase and by a reduction of PARP cleavage, implying a reduction in apoptotic activity. In summary, our results provide evidence that omega-3 and omega-6 fatty acids modulate IGF-I action in colon cancer cells.

Type 2 diabetes mellitus as risk factor for colorectal cancer

Colorectal cancer occurs more frequently in patients with type 2 diabetes mellitus. The hyperinsulinemia-hypothesis suggests that elevated levels of insulin and free IGF-1 promote proliferation of colon cells and lead to a survival benefit of transformed cells, ultimately resulting in colorectal cancer. In patients with type 2 diabetes mellitus, epidemiological studies show an increased risk for colorectal cancer and an even higher risk if patients are treated with sulphonylureas or insulin. Moreover, tumour progression at hyperinsulinemia is more rapid and tumour-associated mortality is increased. Colorectal cancer can be avoided by screening. Recommendations for colorectal cancer screening should employ the recent epidemiologic evidence. All patients with type 2 diabetes mellitus should be recommended to undergo colonoscopy before starting insulin therapy, and screening intervals should not exceed 5 years. For this concept, a review of the evidence is presented, and a screening algorithm for colorectal cancer in patients with type 2 diabetes mellitus is proposed.