Diabetes-Related Complications and Pancreatic Cancer Incidence in the Multiethnic Cohort

Severity of Complications and Duration of Type 2 Diabetes and the Risk of Cancer: A Population-Based Study

BACKGROUND

The literature on the association between diabetes severity and cancer risk is limited and inconclusive. The study aimed to evaluate the association between the adapted Diabetes Complications Severity Index (aDCSI) and the duration of type 2 diabetes and cancer risk.

METHODS

Patients ages 20 years or older with newly diagnosed type 2 diabetes between January 1, 2007, and December 31, 2011, were identified from Taiwan National Health Insurance claims data. Standardized incidence ratios (SIR) were calculated to compare cancer incidence in people with diabetes with that in the general population. Poisson regression was used to examine whether SIRs differed by age, sex, aDSCI, and duration of diabetes.

RESULTS

A total of 756,547 patients were included, with a median follow-up of 8.8 years. Excluding the first year after diagnosis, the SIR for overall cancer was 1.18 [95% confidence interval (CI) 1.17-1.19]. Higher aDCSI was associated with increased SIRs for overall [SIR ratio 1.03 (1.02-1.03) per point increase], head and neck (1.03; 1.01-1.04), liver (1.04; 1.03-1.05), pancreas (1.03; 1.00-1.05), kidney (1.13; 1.10-1.15), and leukemia (1.09; 1.06-1.13). There was no association between aDCSI and colorectal, extrahepatic biliary tract, uterus and thyroid cancer, and a negative association with breast cancer (0.97; 0.95-0.98). Type 2 diabetes duration was associated with increased SIRs for overall [1.01 (1.00-1.02) per year increase], head and neck (1.03; 1.01-1.05), and liver cancer (1.04; 1.02-1.05).

CONCLUSIONS

The heterogeneity in the association between diabetes severity and diabetes-related cancers suggests diverse underlying connections.

IMPACT

Adopting distinct approaches in further research and prevention strategies for different kinds of diabetes-related cancers is important.

OUP accepted manuscript

Background

Methods

Results

Conclusions

Metformin inhibits tumor growth and affects intestinal flora in diabetic tumor-bearing mice

Many studies have found that diabetes increases the risk of some cancers such as hepatocellular carcinoma. However, there are few studies on the relationship between the two diseases and their effects on intestinal flora. Therefore, we used streptozotocin and high-fat diet to establish a mouse model of type 2 diabetes, and then inoculated the Huh-7 hepatocellular carcinoma cells to obtain mouse diabetic tumor model. Mice inoculated with Huh-7 cells alone served as control. The tumor size in the diabetic tumor group was significantly higher than that in the tumor group. Our study also showed that the expression levels of inflammation-related factors (TNFα, IL-1β, IL-6, TLR4 and MCP1) in the diabetic tumor group were significantly higher than that in the tumor group. We found that metformin alleviated blood glucose level, reduced the expressions of inflammation-related factors and retarded xenograft tumor growth in the diabetic tumor group, but it couldn't reduce the tumor growth in the tumor group. Subsequent studies found that the content of some short chain fatty acids (SCFAs) including acetic acid, propionic acid and isobutyric acid decreased significantly in diabetic tumor group. Metformin increased short chain fatty acid levels (acetic acid, butyic acid and valeric acid) and enriched the abundance of SCFA-producing bacterial genera such as Ruminococcaceae, Clostridiales, Anaerovorax, Odoribacter and Marvinbryantia. In conclusion, type 2 diabetes could promote the growth of hepatoma cells in mice. Metformin could inhibit the growth of tumor under the condition of diabetes and play a role in the intestinal homeostasis in mice.