Type II diabetes means that a person is diabetic because his cells do not respond to insulin. Recent research shows type II diabetes is linked to gut bacteria that invade the inner lining of the colon, while the dominant bacteria of most non-diabetics do not try to invade the inner lining of their colon (Cellular and Molecular Gastroenterology and Hepatology, June 2017).
Diabetics who had not had complications such as heart attacks or strokes were given routine colonoscopies to screen for colon cancer at the Veteran's Administration Hospital in Atlanta. Doctors took biopsies from the inner lining of the left descending (last) part of the colon and analyzed them for bacterial invasion using immunofluorescent staining. The diabetics had bacteria that invaded their colon linings while non-diabetics had mostly bacteria that did not invade the inner linings of their colons. The greater the distance that the bacteria invaded the colon linings, the more abnormal tests that measure diabetic damage, such as higher fasting-blood-sugar levels and hemoglobin A1C, became.
Earlier Studies in Mice
Previous studies have shown that bacteria that can pass through the inner linings of the gastro-intestinal tract, respiratory tract, and skin raise markers of inflammation that are associated with high blood sugar levels and obesity in mice (Nature, Feb 25, 2015). Bacteria that do not invade the inner linings of the colon are far less likely to be associated markers of inflammation or with high blood sugar levels and other markers of diabetes.
How These Invading Bacteria May Cause Diabetes
Your ability to respond to insulin to keep your blood sugar levels from rising too high is directly related to an overactive immunity called inflammation. If you have colon bacteria that are trying to get into your bloodstream, your immunity responds by producing white blood cells and chemicals that try to kill the invading germs. Colon bacteria that are not trying to get into your bloodstream do not cause inflammation so your immunity can remain relatively dormant. These non-invading bacteria can be useful because they help to break down food so that you can absorb its nutrients (Nat Rev Immunol, 2010;10:159–169). However, people who have inflammatory bowel diseases have an overactive immunity caused by bacteria that burrow into and through the linings of their intestines (Gastroenterology. 2011;140:1720–1728). Mice that have high blood sugar levels also have these same types of bacteria that try to invade their intestinal linings to turn on their immunities to cause inflammation (Gastroenterology, 2014; 147: 1363–1377). Transferring colon-invading bacteria from diabetic mice to healthy mice causes them to become diabetic (PLoS Biol. 2011; 9: e1001212). Anti-diabetic drugs did not change the invading bacteria in the colons of diabetic mice (Cellular and Molecular Gastroenterology and Hepatology, June 2017).
• The foods that you eat determine which types of bacteria live in your colon because the bacteria in your colon eat the same foods that you do.
• The types of bacteria that invade your colon lining are the ones that turn on your immunity to cause inflammation that prevents your cells from responding to insulin. When you lose your ability to respond to insulin, you have type II diabetes.
• Accumulating evidence shows that avoiding the foods that foster the growth of colon-invading bacteria helps to both prevent and treat diabetes.
• These studies help to explain why you can both help to prevent and treat diabetes by restricting red and processed meat, sugared drinks including fruit juices, sugar-added foods and fried foods; and eating lots of fruits, vegetables, whole grains, beans, seeds and nuts.