More than 30 million adults in North America suffer from diabetes and another 85 million have pre-diabetes that is likely to become full-blown diabetes within five years. Research papers published this month suggest that people who are diabetic or likely to become diabetic should eat a very large amount of plant fiber and restrict animal products, particularly red meat and processed meats.

• Eating lots of fiber from plants can lower high blood sugar by changing the bacteria in your colon. In this study, feeding mice very large amounts of plant starches and fibers and then giving them acarbose, a drug that slows the digestion and absorption of carbohydrates, reduced the rise in blood sugar after meals, and increased growth of healthful colon bacteria called Bacteroidaceae and Bifidobacteriaceae and decreased the harmful bacteria Verruocomicorbiacea and the Bacteroidales S24-7 (mSphere, Feb 6, 2019).

• Researchers can predict which people will develop diabetes by the type of bacteria in their colons more accurately than by measuring the amount of refined carbohydrates and calories they eat (JAMA Network Open, Feb 8, 2019).

• A group of 279 vegetarians had lower fasting insulin levels and higher insulin sensitivity, compared to a matched group of omnivores (Nutrition, Metabolism & Cardiovascular Diseases, February 06, 2019). High insulin levels and low insulin sensitivity are markers of pre-diabetes.

These studies support the many earlier studies that have shown that people who eat diets high in plant fiber, and low in animal saturated fats and animal protein, are far less likely to suffer from diabetes, heart disease and premature death (Eur J Epidemiol, 2018;33(9):883–893). A vegetarian diet helps to lower high blood sugar levels and treat diabetes (Diabetes Spectrum, May 2017;30(2): 82-88). Eating too much meat and too few vegetables markedly increases risk for diabetes (PLoS Med, 2016;13(6):e1002039), and vegetarians have a lower rate of diabetes than meat eaters (Nutr Metab Cardiov Dis, 2013;23(4):292–299). Replacing meat with fruits and vegetables can markedly reduce diabetes risk (Healthcare (Basel), Jun 2017; 5(2): 29).

How Fiber Prevents and Treats Diabetes
The Finnish Diabetes Prevention Study showed that people who eat large amounts of fiber are less likely to develop diabetes, most likely because colon bacteria convert fiber into indolepropionic acid, a short chain fatty acid (SCFA) that blocks inflammation and lowers high blood sugar levels (Sci Rep, Apr 11, 2017;7:46337). This study used whole grains such as rye, barley and oats, and legumes (dried beans, peas and lentils).

You have more than 100 trillion bacteria living in your colon, the last five feet of your intestinal tract. The good bacteria stay in your colon and do not try to penetrate it, but the bad bacteria try to penetrate the cells that line the colon. Your immune system works to kill the bad bacteria before they can escape into your bloodstream. As the bad bacteria keep on trying to get into your cells and bloodstream, your immune system stays active all the time to cause inflammation that can eventually attack your own cells and damage every type of cell in your body. This is why the good bacteria are called anti-inflammatory and the bad bacteria are pro-inflammatory.

The good bacteria produce large amounts of SCFAs that:
• feed them and help the colony of good bacteria to grow,
• turn down inflammation,
• help to lower high blood sugar levels,
• reduce hunger, and
• help to grow and protect the mucous lining your colon, which helps to prevent the colony of bad bacteria from growing and penetrating the colon walls.

Soluble fiber in many fruits, vegetables, nuts and whole grains is made up of chains of sugar molecules that cannot be broken down by human enzymes. Soluble fiber passes to the colon where it fosters the growth of good bacteria that convert the soluble fiber to SCFAs. SCFAs decrease the activity of an overactive immune system and lower high blood sugar and cholesterol. Previous studies have shown that metformin, the most prescribed diabetic drug in the world, lowers high blood sugar levels by raising colon levels of the good colon bacteria, Bifidobacterium and Akkermansia (Nature Medicine, 2017;23:850–858).

Why Meat Increases Risk for Diabetes
Many studies associate eating red meat with increased risk for diabetes (JAMA Intern Med, Jul 22, 2013;173(14):1328-35), while a vegetarian diet is associated with lower risk, probably because it helps to lower high blood sugar levels (Diabetes Spectrum, May 2017;30(2):82-88). Most cases of Type II diabetes are caused by a person’s cells not being able to respond to insulin (insulin resistance). Just four weeks on a high-meat diet increased risk for people not being able to respond to insulin (Metabolism, March 2017;68:173–183) as did four weeks on a high dairy diet (American Journal of Clinical Nutrition, Dec 17, 2015). Animal-based foods such as red meat, processed meat, and eggs are associated with increased risk for becoming diabetic (Eur J Epidemiol, 2017;32(5):363–375; Am J Epidemiol, 2016;183(8):715-728).

When blood sugar levels rise after you eat, your pancreas releases insulin which drives sugar from the bloodstream into your cells. Insulin resistance means that your cells do not respond to insulin’s signal to let the sugar enter them, so insulin remains outside your cells and blood sugar rises to high levels to make you diabetic. Eating red meat causes insulin resistance (Current Developments in Nutrition, April 1, 2017;1(4):e000299). Insulin also drives amino acids, the basic protein building blocks, into cells. Eating meat can cause high rises in insulin which are associated with insulin resistance and increased risk for diabetes.

My Recommendations
Because high blood sugar levels can damage every cell in your body, I think virtually everyone should follow a diet that helps to prevent high rises in blood sugar. This includes:
• Eating vegetables, nuts and other unprocessed plant foods that are full of the fiber that helps to prevent diabetes
• Limiting or avoiding meat and other animal products
• Limiting or avoiding processed plant foods, particularly foods and drinks with added sugars and foods made from flour (bread, pasta, many dry breakfast cereals, pretzels, bagels and so forth)
High blood sugar levels can also be reduced by exercising and losing excess weight.

Checked 6/20/23