What is the role of insulin in the etiology of prostate cancer?

Updated: Oct 11, 2019
  • Author: Mark A Moyad, MD, MPH; Chief Editor: Edward David Kim, MD, FACS  more...
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An intriguing theory suggests a role for insulin in the promotion of cancer. Insulin is an important growth factor, and levels of insulin growth factor and its receptor have been shown to be elevated in persons with prostate cancer. Keeping insulin values low may retard the growth rate of prostate cancer cells; this can be achieved only through diet.

A glycemic index has been developed for persons with diabetes, so that they can take advantage of the small amounts of insulin they may produce. This index ranks carbohydrates in different foods on a scale of 0-100, depending on how much those foods increase blood sugar levels after consumption. The consumption of low-glycemic foods lowers blood sugar levels and decreases insulin production. According to this theory, low levels of insulin growth factor would prevent cancer cells from growing as rapidly.

In the 1920s, Ohsawa popularized the concept of a macrobiotic diet, which comprises foods with a very low glycemic index. This stringent diet consists primarily of whole grains and vegetables. Even most fruits are excluded. In contrast, the diabetic diet restricts only those foods with the highest glycemic index, such as the following:

  • Dates
  • Corn flakes
  • Jelly beans
  • Doughnuts
  • White bread
  • Table sugar
  • White rice

The renewed focus on the role of insulin in preventing or slowing the progression of prostate cancer and other cancers is exemplified by the interest in using metformin for that purpose. [6, 37, 38] Nevertheless, while the Diabetes Prevention Program trial demonstrated that metformin has the ability to prevent type 2 diabetes, an underappreciated finding of that trial was the profound reduction in diabetes risk produced by lifestyle changes (a low-fat diet with total caloric reduction of 450 calories/day and 150 minutes of exercise/week). In fact, lifestyle changes proved significantly more effective than metformin for diabetes prevention (58% versus 31% reduction). [39] Once again, this illustrates the value of an integrated approach to health promotion and disease prevention.

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