A review of 28 studies found that risk for type II diabetes was increased by 36 percent for every 100 grams of meat from mammals or 50 grams of processed meat eaten each day (Diabetes Metab, Oct 2020;46(5):345-352). This increased risk was associated with higher blood levels of TMAO from the choline and lecithin in meat (PLoS One, Jan 15, 2020). A study that followed 63,257 Chinese adults, aged 45–74, for an average of 10.9 years found that eating red meat was associated with increased risk for developing diabetes (American Journal of Epidemiology, May 23, 2017) as did many other studies (JAMA Intern Med, Jul 22, 2013;173(14):1328-35; Nutrients, 2014 Feb; 6(2): 897–910; Diabetes Care 2004 Sep; 27(9):2108-2115; Am J Epidemiol,(2016) 183(8):715-728). Vegetarians have a significantly lower incidence of type II diabetes than people who eat meat (Diabetes Spectrum, May 2017;30(2):82-88).

How Eating Meat from Mammals Increases Diabetes Risk
Most cases of diabetes are caused by insulin resistance (not being able to respond to insulin). After just four weeks on a high-meat diet, people were less able to respond to insulin (Metabolism, March 2017;68:173–183). Meat contains two chemicals called choline and lecithin that pass all the way to the last five feet of your intestinal tract (your colon), which contains more than 100 trillion bacteria (PLoS Biol, Aug 2016;14(8):e1002533). Some of these bacteria are healthful, but others are harmful because they convert choline and lecithin into a chemical called TriMethylAmine (TMA). The TMA is absorbed into your bloodstream and travels to your liver, which converts TMA to TriMethlAmineOxide or TMAO (N Engl J Med, Apr 25, 2013;368(17):1575–1584). A diet high in meat and other animal products can markedly increase the growth of the harmful colon bacteria that raise TMAO levels and reduce the growth of healthful bacteria that lower TMAO levels (Molecular Nutrition and Food Research, July 5, 2016).

High blood TMAO is associated with high blood sugar levels. Mice fed TMAO developed high blood sugar levels, high fasting insulin levels and signs of an overactive immune system called inflammation (J of Bioscience and Bioengineering, 2014;118(4):476–81). The same associations have been found in humans (The Am Journal of Clin Nutrit, 2017;106(3):888–94).

My Recommendations
I have reported on many studies on reducing risk for heart attacks by limiting meat, but this new report reminds us that eating mammal meat is associated with increased risk for type II diabetes as well. High levels of TMAO are also associated with increased risk for strokes, certain cancers and premature death. A high-plant diet that is low in mammal meat and other animal products will help to maintain a colony of healthful colon bacteria.
More Vegetables, Less Diabetes
Bad Colon Bacteria May Cause Heart Attacks
Dementia Risk Increased by Harmful Bacteria in Your Colon