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Diabetes and Cancer

How are Diabetes and Cancer Connected?

Over 29 million people in the United States have type 2 diabetes. The dangerously high prevalence of overweight and obesity is at the heart of this problem. Diabetes is the seventh leading cause of death in the United States, is the leading cause of blindness and kidney failure in adults, and doubles the risk of heart attack and stroke.1,2

Diabetes also increases the risk of several cancers. In a number of studies, diabetic patients have been shown to have an elevated risk of colorectal cancer and non-diabetics with elevated postprandial glucose levels also have a higher risk of colorectal cancer than individuals with normal glucose tolerance.3,4 A review that analyzed data from several studies found that diabetic patients are 30% more likely to develop colorectal cancer, 20% more likely to develop breast cancer, and 82% more likely to develop pancreatic cancer.5-7

How could diabetes influence the development of cancer? The high blood glucose levels and the resultant elevated insulin response associated with type 2 diabetes, affect all tissues of the body. It has been hypothesized that diets high in sugars and white flour increase the risk of cancers because of their impact on these factors, particularly elevated insulin.

Scientists believe that insulin therapy and elevated insulin levels contribute to the association between diabetes and colorectal cancer. Insulin in high concentrations may bind to the receptor for a growth factor called insulin-like growth factor 1 (IGF-1) — this interaction has the potential to promote the growth and division of cancer cells. Cancerous cells also often have elevated levels of insulin receptors, and when insulin binds these receptors it has growth-promoting effects.6

There is much evidence supporting the possibility that chronic exposure to diets rich in refined carbohydrates may act directly to promote cancer development. Foods with a high glycemic load (such as sugar and white flour products) produce dangerous spikes in blood glucose, consequently resulting in high insulin production. Diets including large quantities of high GL foods increase the risk of several chronic diseases, including cancers.8 For example, a meta-analysis of many studies found a 26% increase in colorectal cancer risk in people who consumed the most high glycemic load foods in their diets.9

The best diet for preventing or reversing diabetes is also the best diet for cancer protection. It is a diet with a high nutrient per calorie ratio — including lots of green and non-starchy vegetables, beans, raw nuts and seeds, and some fresh fruit; animal products; and avoiding sweeteners, oils and white flour. The high levels of dietary micronutrients fuel cellular repair, reduce body fat and heal the body from the inside out, resulting in a dramatic reversal of heart disease, and diabetes, offering dramatic protection against cancer.


1. American Diabetes Association: Diabetes statistics [http://www.diabetes.org/diabetes-basics/statistics/ 
2. U.S. Centers for Disease Control and Prevention. National Diabetes Fact Sheet.[http://www.cdc.gov/diabetes/pubs/estimates11.htm 
3. La Vecchia C, D'Avanzo B, Negri E, et al: History of selected diseases and the risk of colorectal cancer. Eur J Cancer1991, 27:582-586.
4. Schoen RE, Tangen CM, Kuller LH, et al: Increased blood glucose and insulin, body size, and incident colorectal cancer.J Natl Cancer Inst 1999, 91:1147-1154.
5. Experts call for further research into the relationship between insulin therapy and cancer. In EurekAlert!; 2010.
6. Vigneri P, Frasca F, Sciacca L, et al: Diabetes and cancer. Endocr Relat Cancer 2009, 16:1103-1123.
7. Pisani P: Hyper-insulinaemia and cancer, meta-analyses of epidemiological studies. Arch Physiol Biochem 2008, 114:63-70.
8. Barclay AW, Petocz P, McMillan-Price J, et al: Glycemic index, glycemic load, and chronic disease risk--a meta-analysis of observational studies. Am J Clin Nutr 2008, 87:627-637.
9. Gnagnarella P, Gandini S, La Vecchia C, et al: Glycemic index, glycemic load, and cancer risk: a meta-analysis. Am J Clin Nutr 2008, 87:1793-1801.

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