Gut bacteria and diabetes

======================= The link between gut bacteria and diabetes In recent years, significant progress has been made in the field of *human microbiome*, which has made researchers have a new look at the hidden factors in the occurrence of chronic diseases, including diabetes. One of the most important findings is that the composition and function of gut bacteria can directly or indirectly affect glucose metabolism, the body's response to insulin, and even appetite. To put it simply, the microscopic world living in the human gut plays a role beyond the digestion of food. Some key research in this field shows that the gut microbiome can improve the function of beta cells in the pancreas by producing certain metabolic compounds, such as *short-chain fatty acids* (SCFAs) including butyrate, propionate, and acetate, as well as increasing the cells' sensitivity to insulin. In addition to directly affecting the target cells, these metabolic compounds are also associated with the reduction of systemic inflammation, which is one of the key factors in the occurrence of insulin resistance. Difference of microbial composition in diabetic and healthy people One of the most important issues investigated in the field of microbiome medicine is the direct comparison of the intestinal bacterial composition in healthy people and people with type 2 diabetes. Research has shown that diabetics usually have less microbial diversity and a disturbed balance in the intestinal bacterial population. In healthy people, beneficial bacteria such as **Faecalibacterium prausnitzii**, **Akkermansia muciniphila** and some species of **Bifidobacterium** are abundant. These bacteria help maintain proper gut wall function, reduce inflammation, and produce SCFAs, all of which play a role in blood sugar control. On the other hand, an abnormal increase of some "inflammatory" bacteria such as **Ruminococcus**, **Clostridium**, and species of **Proteobacteria** have been seen in diabetics, which are associated with greater permeability of the intestinal wall (leaky gut), chronic inflammation, and ultimately a decrease in insulin sensitivity. Simply put, in a diabetic person's body, the bacteria that should protect are less, and those that cause inflammation are increased. Also, it has been found that diabetics have less bacteria that break down fiber and convert it into short chain fatty acids. This decrease in SCFA production causes the intestinal wall to become weaker, inflammation to spread throughout the body, and sugar metabolism to be impaired. From a genetic point of view, it is also known that some bacteria are involved in the regulation of certain molecular pathways that are directly related to the function of insulin receptors in cells. Changes in these pathways can lead to a kind of "indifference" of cells to insulin; A phenomenon that is one of the main symptoms of type 2 diabetes. How does an unhealthy microbiome lead to insulin resistance? One of the key factors in the formation of type 2 diabetes is **insulin resistance**; This means that body cells are less sensitive to insulin and cannot absorb sugar from the blood. For many years, scientists thought that this phenomenon was mostly influenced by genetics and nutrition, but the discovery of the influence of **intestinal microbiome** in this field opened a new chapter in the understanding and treatment of diabetes. An unhealthy microbiome can not only prevent cells from absorbing sugar properly, but also activates a chain of inflammatory and metabolic processes that ultimately lead to insulin resistance. Chronic inflammation and intestinal permeability: a gateway to metabolic dysfunction The human intestine has a smart and precise structure. Although the intestinal wall has the task of absorbing nutrients, at the same time, it must prevent pathogens, toxins, and harmful bacteria from entering the bloodstream. This function is guaranteed by a protective layer called tight junctions. Now imagine that this defensive barrier is weakened; In such a case, a phenomenon called "Leaky Gut" occurs. In people with an unhealthy microbiome, there is an increase in species of harmful bacteria that produce inflammatory substances. These substances, such as lipopolysaccharides (LPS), are released from the bacterial wall and, if leaked into the bloodstream, activate extensive inflammatory reactions in the body. In response, the immune system secretes molecules such as TNF-α and IL-6 that instruct cells to remain on alert. What is the result? Due to chronic inflammation, cells lose their sensitivity to insulin. It's as if the body is in a "defensive" mode and instead of normal metabolism, it keeps its energy resources to deal with hypothetical threats. In this condition, glucose remains in the blood and the sugar level rises. This dangerous cycle—starting with gut permeability, LPS passage into the blood, activation of inflammation, and decreased insulin sensitivity—is one of the main mechanisms of insulin resistance caused by an unhealthy microbiome. The role of short chain fatty acids (SCFA) in regulating blood sugar On the other hand, beneficial intestinal bacteria have a special ability to produce vital compounds that have a positive effect on the body's metabolic health. The most important of these compounds are Short Chain Fatty Acids (SCFAs), which are the result of fermentation of indigestible dietary fibers by intestinal microorganisms. The three main SCFAs are: - **Butyrate** - **Propionate** - **Acetate** These compounds have several very vital functions that are directly related to blood sugar regulation: - **Increased sensitivity to insulin:** Butyrate activates pathways in muscle and liver cells that enhance insulin sensitivity. This substance has the role of a "regulator" of metabolism. - **reduction of inflammation:** SCFAs help prevent insulin resistance by reducing the secretion of inflammatory cytokines (such as IL-1β and TNF-α). They can also act on immune cells through specific receptors (GPR41 and GPR43) and suppress inflammatory responses. - **Strengthening the intestinal barrier:** Butyrate especially plays a key role in feeding intestinal cells (enterocytes) and strengthens the structure of strong intercellular bonds. As a result, a healthier gut wall will prevent LPS and toxins from entering the bloodstream. - **regulating the secretion of intestinal hormones:** SCFAs increase the secretion of hormones such as *GLP-1* and *PYY*, which play a role in reducing appetite, increasing insulin secretion, and decreasing glucagon secretion. These factors all help to regulate blood sugar better. But when a person has an unhealthy microbiome – that is, no SCFA-producing bacteria or a low-fiber diet – the production of these beneficial fatty acids decreases. In such a case, not only inflammation increases, but insulin resistance also increases. Role of nutrition in microbiome formation and diabetes control Nutrition is one of the most powerful human tools for shaping the health of the gut microbiome. Unlike genetics, which cannot be changed, diet is completely within an individual's control and can rapidly and directly change the structure and function of the gut bacterial community. In fact, just as unhealthy nutrition can cause the growth of harmful bacteria and increase inflammation, proper nutrition can also improve the intestinal defense barrier by strengthening beneficial bacteria, balance blood sugar levels, and even reduce the risk of type 2 diabetes. Foods That Love Beneficial Bacteria The gut microbiome, like a living ecosystem, needs regular and special nutrition to stay healthy. Some foods such as *vegetable fibers, fermented foods, and polyphenols* can provide conditions for the growth and survival of beneficial bacteria. ### 1-Indigestible fibers: the main fuel for bacteria Soluble fibers found in fruits, vegetables, legumes and whole grains are the main source of nutrition for beneficial bacteria. These bacteria produce short-chain fatty acids (SCFA) through fermentation of these fibers, which have anti-inflammatory and blood sugar-regulating effects. The lack of fiber in the diet causes starvation of good bacteria and, on the contrary, the growth of harmful fungi and bacteria. ### 2- Fermented foods: direct injection of probiotics Traditional fermented foods such as natural yogurt, kefir, kimchi, sauerkraut, tempeh and kombucha contain live and beneficial bacteria (probiotics). Regular consumption of these foods not only increases gut bacterial diversity, but also strengthens species that play a key role in regulating blood sugar and reducing inflammation. ### 3-Polyphenols: Fortifying Phytochemicals Polyphenols are natural compounds found in fruits, green tea, turmeric, bitter cocoa and olives that have strong antioxidant properties. Studies have shown that polyphenols not only directly reduce inflammation, but also change the microbial composition of the gut in favor of beneficial bacteria. ### 4- Avoiding industrial and high-fat foods: Processed foods are rich in saturated fats, added sugars, preservatives, and chemical additives that destroy beneficial bacteria and provide the basis for the growth of inflammatory and pathogenic bacteria. Western diets, full of these substances, directly contribute to the formation of insulin resistance by increasing intestinal permeability and reducing microbial diversity. Effect of fiber and prebiotics on intestinal bacteria Dietary fibers not only play a role in satiety and weight control, but are considered the backbone of a diet beneficial for the microbiome. Besides them, **prebiotics** are known as a special category of fibers that provide selective nutrition for the growth and activity of probiotics. Soluble fiber, by fermentation in the large intestine, produces short chain fatty acids, which were explained in detail in the previous section. Increasing fiber consumption increases the population of bacteria such as *Bifidobacterium* and *Lactobacillus*, which play a role in reducing blood sugar, regulating appetite, and reducing blood insulin levels. ### Prebiotics: special food for probiotics Prebiotics include compounds such as inulin, fructo-oligosaccharides (FOS), and galacto-oligosaccharides (GOS), which are found in foods such as garlic, onions, leeks, asparagus, unripe bananas, oats, and artichokes. These substances reach the large intestine without being digested in the stomach or small intestine and specifically stimulate the growth of beneficial bacteria. Human studies have shown that regular consumption of prebiotics causes: - Increased secretion of GLP-1 and PYY (hormones that reduce blood sugar) - Reduction of false appetite - Regulation of insulin secretion - Reducing systemic inflammation will be ### Increasing microbial diversity with fiber-rich diets: Microbial diversity is a key indicator of gut health and metabolic disease control. Diets high in fiber cause more diversity in gut bacteria, which will lead to metabolic balance and reduce the risk of type 2 diabetes. On the contrary, low-fiber and monotonous diets lead to microbial poverty and an increase in inflammatory species. Lifestyle and its role in improving gut health The gut microbiome is a living and dynamic ecosystem that is influenced by our daily behaviors. Although the diet provides the fuel for this ecosystem, the way this fuel is used and managed is determined by the brain, hormones, physical activity level and sleep pattern. Therefore, having a balanced and healthy lifestyle can help maintain the diversity and balance of beneficial bacteria and inhibit the growth of harmful species, thereby reducing the risk of insulin resistance and diabetes. Exercise, stress and sleep; Factors influencing the microbiome Numerous studies have shown that regular physical activity increases microbial diversity and the growth of anti-inflammatory bacteria. Even people who eat the same diet but exercise have a healthier microbiome. The benefits of exercise on the gut microbiome include: - Increase in SCFA producing bacteria such as **Butyrate** which are vital for the health of the intestinal wall. - Reduction of inflammatory bacteria such as pathogenic species from the genus *Proteobacteria*. - Increase in species such as *Akkermansia muciniphila*, which is related to improving insulin sensitivity and reducing abdominal fat. - Improving bowel movements and reducing constipation, which provides a better environment for the growth of beneficial bacteria. Important note: Even light activities such as daily walking, swimming or yoga can have significant positive effects. Chronic stress; The silent enemy of the microbiome Stress, through the brain-gut axis, has destructive effects on the microbiome. When the body is in a state of chronic stress, excessive secretion of cortisol and other stress hormones causes negative changes in the composition of intestinal bacteria, increasing the permeability of the intestinal wall and decreasing the secretion of immunoglobulin A. These conditions lead to chronic inflammation, leakage of endotoxins into the blood, and eventually insulin resistance. Gut related stress symptoms: - Persistent bloating or changes in bowel movements - Insomnia or light sleep - Loss of appetite or emotional overeating Stress reduction strategies to maintain gut health: - Breathing exercises, meditation and mindfulness (Mindfulness) - Yoga or Tai Chi - Contact with nature and outdoor activities - Writing memories and reducing mental load enough sleep; Regulatory cycle for the body and bacteria Lack of sleep or poor quality sleep directly affects the microbiome balance. Frequent awakenings at night, less than 6 hours of sleep or circadian rhythm disturbances (such as shift work) change the microbial composition, increase inflammatory bacteria and decrease beneficial species. Complications of insomnia related to the intestine: - Increased tendency to eat sugar and simple carbohydrates - Increased levels of cortisol and blood glucose - Decreased response to insulin - Increased intestinal permeability and systemic inflammation **Golden recommendations for healthy sleep:** - Sleeping and waking up at a certain time - Removing the blue light of mobile phones and laptops 1 hour before sleep - Having a light dinner at least 3 hours before going to bed - Proper ventilation and silence in the bedroom A healthy lifestyle plays a fundamental role in the health of the gut microbiome and the prevention of diabetes. Regular exercise, adequate sleep, and stress control are the three main pillars of a healthy lifestyle. Daily behaviors have a direct effect not only on metabolism, but also on the diversity and balance of gut bacteria. Establishing simple but sustainable lifestyle routines will have a great impact on a person's long-term health. **To receive a visit (online or in person) with Dr. Yazdan Panah, fill out the form below**