Diabetes, a Digestive Disorder

Those who have been diagnosed with diabetes are accustomed to the dietary restrictions of their diagnosis; however, most of these dietary guidelines are designed to reduce the intake of glucose and related sugars. Little has been said about the role of nutrients supporting digestive health for the diabetic. Yet research is showing that the integrity of the digestive system plays a crucial role in maintaining normal blood sugar levels and insulin function.

In 1992, researchers first reported that diabetic patients who had a section of their upper digestive tract called the duodenum removed, recovered to normal blood glucose levels within days.[1] In this study involving 163 diabetic patients with hyperglycemia, 141 of the patients recovered to normal carbohydrate metabolism after gastric bypass surgery removing the duodenum, part of the stomach and an upper region of the small intestine. Further studies continue to report approximately 80% recovery following surgeries to remove the duodenum and nearby regions of the digestive track.[2,3,4]

The duodenum, a ten-inch section of the gut between the stomach and the small intestine, is a part of both the digestive system and it is an endocrine gland. In other words, the duodenum both processes food for digestion and secretes hormones. Significant absorption of nutrients occurs in the duodenum, which is near the top of the digestive system. According to Dr. Ronald Sawaya and fellow researchers from Temple University, “The majority of micronutrient and trace element absorption occurs in the duodenum and proximal jejunum.”[5] The digestion of protein is completed in the duodenum by pancreatic enzymes called proteases. Most vitamins enter the bloodstream via passive diffusion across the mucosal membranes of the digestive track. Minerals, vitamins and trace elements such as selenium are absorbed before reaching the colon. Ninety percent of the fluids we consume are absorbed from the duodenum and the small intestine, to prevent dehydration and help maintain fluid balance in the body. The enterocyte cells that line the duodenum absorb iron. These same cells play a role in the absorption of calcium and other minerals such as phosphate, though these minerals can be absorbed in the small intestine as well. Vitamins A and B1, folate, calcium, glycerol, fatty acids, monoglycerides, amino acids, monosaccharides, and disaccharides are absorbed from the duodenum. Studies have shown that removal of the duodenum results in significant nutritional deficiencies.[6] Though surgery to remove the duodenum may reduce blood sugar levels, it does so at a great risk of malnourishment.

The duodenum also secretes hormones, called incretins and anti-incretins, which serve to regulate pancreatic function. The pancreas is where insulin is produced. Incretin hormones stimulate the pancreas to produce insulin, whereas anti-incretins cause the pancreas to stop producing insulin. 

The pancreas has two type of cells, beta cells which produce insulin, and alpha cells which secrete the hormone glucagon which elevates the glucose levels in the blood.  When the duodenum senses nutrients being absorbed through its mucosal walls, it responds by releasing incretin hormones such as the glucagon-like peptide (GLP-1). GLP-1 activates the pancreatic beta cells to produce insulin that will then transport glucose from your blood into the cells in your body. It makes sense that this system is activated when you eat food; when nutrients become available, the duodenum secretes incretins to inform the pancreas to produce insulin to feed these nutrients to your hungry cells.

When the duodenal walls are damaged, however, they actually produce anti-incretins that cause the pancreatic beta cells to convert to alpha cells, which do not produce insulin. The pancreas then becomes dysfunctional, and one suffers from reduced insulin function. As a result of low levels of insulin and high levels of glucagon from the alpha cells, glucose levels begin to build up in the blood. Without insulin to transport the glucose into the cells, one will suffer from fatigue and loss of energy, and begin to crave sugary foods to try to feed these hungry cells. However, no amount of sugar will fulfill these cellular cravings since there is no insulin to transport the glucose into the cells!  It becomes a vicious cycle of craving, fatigue, and high blood sugar.

When doctors remove the duodenum, they remove the part of the digestive system that is producing the anti-incretins – which are blocking the pancreas from producing insulin.  Removing the duodenum and other forms of gastric bypass surgery do appear to normalize blood sugar levels. But this occurs at a sacrifice to one’s nutritional status.  Removal of the duodenum has other adverse effects on health, involving iron deficiency (anemia), folate deficiency, and other nutrient deficits. Bariatric surgery is emerging as an effective means of controlling blood sugar but ignores associated side effects.  Malabsorption of essential vitamins and minerals occurs along with substantial weight loss, and results in nutritional deficiencies and related functional consequences. Medical researchers continue to explore ways of restoring normal blood sugar and insulin levels without causing harm to other systems of the body.

Why does the duodenum get damaged in the first place? Many things can cause damage to the duodenum, often with cumulative effects over time. Antibiotics kill the gut bacteria that are so important to maintaining a healthy gut. When the gut flora is damaged, we are more vulnerable to unhealthy bacteria like h-pylori which cause further damage and are associated with ulcers in the duodenum. In addition to unhealthy bacteria, molds, fungus and viruses can also damage the duodenum. In fact, researchers wanting to study diabetes in animals force the animals to become diabetic by exposing them to mold or bacteria like streptozotocin[7]. While researchers claim that they do not know specifically how these infections cause diabetes in animals, it is likely that they do so by damaging the digestive system and nutrient absorption.

Drugs and other chemicals can also damage the duodenum and other parts of the digestive system. Some pesticides and herbicides target the cells lining the gut and kill the gut flora. For example, glyphosate (Roundup), an herbicide used in growing many foods, has been shown to kill the gut flora, promoting the growth of harmful bacteria, and significantly damaging the mucosal lining of the duodenum[8]. As a result of glyphosate damage to the duodenum, signals to the pancreas are interrupted, and glucose and insulin regulation fail[9] .

Medications such as non-steroidal anti-inflammatory drugs, prednisone[10] , alcohol[11] , bisphosphonates (for osteoporosis), and methyltrexate[12]  also damage the digestive system and can affect pancreatic function.

Recently, researchers have explored the possibility of healing the gut and restoring normal function to the duodenum. Many medical researchers recognize that “Because the etiology of many diseases is largely correlated with the intestinal microbiome, a balance between the host immune system and the commensal gut microbiota is crucial for maintaining health.”[13] A key factor in restoring healthy gut flora and healing the duodenum is treatment with probiotics. There are numerous supplements on the market touting thousands if not millions of different types of probiotics. In the past five years, the National Institutes of Health has made testing of probiotic supplements a high priority research area, suggesting the worthiness of exploring the use of probiotics in improving your own health. Restoring healthy gut bacteria can help to heal the duodenum and other areas of the gut, avoid unnecessary surgery and restore health to the individual.

In addition to supplementing with probiotics, nutrients have been identified that help to heal the gut, and the duodenum specifically. L-glutamine protects and helps heal the duodenum, improving antioxidant status. Perhaps related to improved gut integrity, studies have also shown that l-glutamine supplementation can lower high blood sugar and restore normal insulin function.[14] 

Studies have shown that bioflavinoids such as quercetin also have a neuroprotective effect on the duodenum. Quercetin improves digestive health, consequently ameliorating hyperglycemia and oxidative stress, by healing the gut and blunting free radical-induced toxicity.[15, 16]

The bio-active ingredients of natural foods such as green tea (epigallocatechins) and citrus polyphenols can inhibit the growth of bad bacteria such as H. pylori, Staphylococcus aureus, E. coli, and Salmonella typhimurium, which are associated with duodenal ulcers.  These nutrients also serve to relieve oxidative stress and heal the gut. Cinnamon and extracts of Ceylon cinnamon oil are very effective means of eliminating H. pylori and other bacteria associated with the formation of ulcers in the duodenum. This antimicrobial action may account for the potent effect that cinnamon has in lowering blood sugar levels.[17]

Taken together, these findings suggest that, at least in some instances, damage to the duodenum may account for the development of high blood sugar and even eventually insulin deficiency. Though surgery to remove the duodenum has been effective in lowering blood sugar, surgery also results in essential nutrient deficiencies that may be a greater risk than benefit. Healing the gut may provide an essential treatment to resolve an underlying cause of diabetes. Nutrients and supplements such as probiotics, l-glutamine, quercetin, and foods such as cinnamon and green tea may help in healing the gut, lowering blood sugar and restoring normal pancreatic and insulin function.

In summary:

1. Removing the duodenum seems to resolve diabetes, suggesting that diabetes is related to damage in this part of the digestive system. 

2. Although blood sugar normalizes following duodenal surgery, nutrient deficiencies can result and cause other significant health problems. The risks of surgery may outweigh the benefits.

3. Many medications such as NSAIDS, prednisone and other chemicals such as pesticides and herbicides can cause damage to the duodenum. 

4. Probiotics, digestive enzymes, and nutrients such as l-glutamine and antioxidants help to heal the digestive system. Raw healthy diets including high intake of vegetables, fruits, legumes, raw nuts, and green tea can also restore health and normalize blood sugar and insulin function in the Type II diabetic.

5. Probiotics, L-glutamine, quercetin, cinnamon, anti-oxidants and a diet of whole foods may be effective in the treatment of Type II diabetes, and provide a safer alternative to surgery.


[1] Pories, MacDonald Morgan et al., Surgical treatment of obesity and its effect on diabetes, 1992, American J. of Clinical Nutrition.

[2] de Jonge C, Rensen SS, Verdam FJ, Vincent RP, Bloom SR, Buurman WA, le Roux CW, Schaper NC, Bouvy ND, Greve JW, Endoscopic duodenal-jejunal bypass liner rapidly improves type 2 diabetes. Obes Surg. 2013 Sep;23(9)

[3] Francesco Rubino, Tracy-Ann Moo, Daniel J. Rosen, Greg F. Dakin, and Alfons Pomp, Diabetes Surgery: A New Approach to an Old Disease, Diabetes Care, 2009 Nov; 32(Suppl 2): S368–S372.

[4] W J Pories, M S Swanson, K G MacDonald, S B Long, P G Morris, B M Brown, H A Barakat, R A deRamon, G Israel, J M Dolezal, Who would have thought it? An operation proves to be the most effective therapy for adult-onset diabetes mellitus, Ann Surg. 1995 Sep; 222(3): 339–352.

[5],[6] Sawaya RA, Jaffe J, Friedenberg L, Friedenberg FK, Vitamin, Mineral, and Drug Absorption Following Bariatric Surgery. Curr Drug Metab. 2012, Nov; 13(9): 1345-1355.

[7] A. Akbarzadeh, D. Norouzian, M. R. Mehrabi, Sh. Jamshidi, A. Farhangi, A. Allah Verdi, S. M. A. Mofidian, and B. Lame Rad, Induction of diabetes by Streptozotocin in rats, Indian J Clin Biochem, 2007 Sep; 22(2): 60–64.

[8] Shehata AA, Schrodl W, Aldin AA, Hafez HM, Kruger M. The effect of glyphosate on potential pathogens and beneficial members of poultry microbiota in vitro. Current Microbiology. 2013 April;66(4):350-8. 

[9] Samsel A and Seneff S, Glyphosate, pathways to modern diseases II: Celiac sprue and gluten intolerance Interdiscip Toxicol., 2013 Dec; 6(4): 159–184.

[10] I. A. Kellock and G. Sclare, Fatal Duodenal Perforation during Prednisone Therapy. Br Med J.  1957 Apr 20; 1(5024): 930–931.

[11] Baliunas DO, Taylor BJ, Irving H, Roerecke M, Patra J, Mohapatra S, Rehm J.  Alcohol as a risk factor for type 2 diabetes: A systematic review and meta-analysis.

Diabetes Care. 2009 Nov;32(11):2123-32.

[12] Tomoya Tsukada, Tatsue Nakano, Takashi Miyata, and Shozo Sasaki, Life-Threatening Gastrointestinal Mucosal Necrosis during Methotrexate Treatment for Rheumatoid Arthritis, Case Rep Gastroenterol. 2013 Sep-Dec; 7(3): 470–475.

[13] Aleksandra DudaChodak, Tomasz Tarko, Paweł Satora · Paweł Sroka, Interaction of dietary compounds, especially polyphenols, with the intestinal microbiota: a review

Eur J Nutr (2015) 54:325–341.

[14] Opara EC, Petra A, Tevrizian A, Feinglos MN Surwit RS, L-glutamine supplementation of a high fat diet reduces body weight and attenuates hyperglycemia and hyperinsulinemia in C57BL/6J mice. J. Nutr. 1996 Jan;126(1):273-9.

[15] Lopes CR, Ferreira PE, Zanoni JN, Alves AM, Alves EP, Buttow NC, Neuroprotective effect of quercetin on the duodenum enteric nervous system of streptozotocin-induced diabetic rats. Dig Dis Sci. 2012 Dec;57(12):3106-15.

[16] Alam MM, Meerza D, Naseem I, Protective effect of quercetin on hyperglycemia, oxidative stress and DNA damage in alloxan induced type 2 diabetic mice, Life Sci. 2014 Jul 25;109(1):8-14.

[17] Khan A, Safdar M, Ali Khan MM, Khattak KN, Anderson RA, Cinnamon improves glucose and lipids of people with type 2 diabetes, Diabetes Care, 2003 Dec;26(12):3215-8.

Debbie Norris

Debbie Norris

Deborah Norris, Ph.D. is author of In the Flow: Bridging the Science and Practice of Mindfulness, and Editor-in-Chief of MindBodyJournal.com. Dr. Norris is Founder of The Mindfulness Center™, based in Washington, D.C. She is Psychologist-in-Residence and Director of the Psychobiology of Healing Program at American University, and past professor at Georgetown University Medical School. Renowned for her online meditation teacher programs, The Science of Mindful Awareness (SOMA), Dr. Norris is an internationally recognized speaker and educator on mindfulness, yoga, and integrative mind-body therapies. A health scientist with over 40 years of experience ranging from traditional medical and psychotherapeutic practices to integrative therapies and lifestyle practices, she teaches and conducts research in mindfulness, behavioral medicine and other holistic approaches to happiness and well-being.

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