Diabetes and the microbiome: how bacteria control sugar levels

Світлана Бурмей
3 days ago
5 min read

Біговий захід GoMove в Ужгороді за підтримки Ediens

Type 2 diabetes mellitus (T2DM) is a growing global health problem that is closely related to the obesity epidemic. It is one of the most common non-communicable diseases in the world, characterized by disorders of carbohydrate, lipid and protein metabolism, and arises from impaired insulin secretion, cellular resistance to insulin or a combination of these factors. Typical clinical markers of T2DM are elevated levels of glucose, glycosylated hemoglobin, cholesterol, triglycerides and low- and very-low-density lipoproteins.

Traditionally, it was believed that the root causes of type 2 diabetes were exclusively genetics, physical inactivity, and poor diet. However, today the scientific world is experiencing a real revolution: the latest studies have proven that the development of chronic low-grade systemic inflammation, which underlies insulin resistance, is a direct consequence of changes in the intestinal microbiome. Intestinal bacteria have turned out to be not just "cohabitants" of our body, but powerful regulators of energy balance and glucose metabolism.

Dysbiosis in diabetes: what microbes are we losing?

Each person’s microbiome is unique, but patients with type 2 diabetes have a distinct pattern of bacterial imbalance, known as dysbiosis. Studies have shown that most patients with diabetes have a dramatic decline in the levels of beneficial bacteria, including Bifidobacterium and Lactobacillus . The vacated ecological niches are quickly filled by opportunistic pathogens, with populations of Bacteroides , Prevotella , Clostridium , Proteus , Staphylococcus , Candida , and Enterococcus increasing .

A critical indicator of diabetes is the loss of butyrate-producing bacteria. In particular, diabetics have significantly reduced numbers of beneficial microorganisms such as Roseburia intestinalis and Faecalibacterium prausnitzii , as well as a bacterium that specializes in breaking down mucin (slime) and maintaining intestinal barrier function, Akkermansia muciniphila . The reduction in the number of these strains has a direct correlation with the development of type 2 diabetes and insulin resistance.

How exactly bacteria control sugar: three key mechanisms

According to current scientific evidence, the intestinal microbiota controls glucose metabolism and overall energy homeostasis through three main molecular mechanisms: the short-chain fatty acid (SCFA) theory, the bile acid theory, and the endotoxin theory.

1. Short-chain fatty acid (SCFA) theory

CLFA are products of bacterial fermentation of indigestible carbohydrates (dietary fiber) in the large intestine. They mainly include acetate, propionate, and butyrate. These acids are able to acidify the intestinal environment, inhibiting the growth of pathogens, and serve as the main source of energy for epithelial cells (enterocytes).

However, the most important function of CLFA is that they work as signaling molecules, binding to specific receptors (G-coupled receptors) and influencing the immune system and metabolism. Butyrate plays a key role in maintaining the integrity of the intestinal barrier, protecting the body from systemic inflammation. A decrease in butyrate levels leads to a decrease in the stimulation of pancreatic secretion, resulting in a decrease in insulin levels and a decrease in overall tissue sensitivity to insulin. In turn, propionate is able to reduce cholesterol synthesis in the liver and improve lipid metabolism.

2. Endotoxin theory (metabolic endotoxemia)

Gram-negative bacteria contain lipopolysaccharides (LPS) in their outer membrane, so-called bacterial endotoxins. A diet high in fat and sugar leads to dysbiosis, reducing the number of lacto- and bifidobacteria and increasing the proportion of gram-negative flora. This causes degradation of the protective mucosal barrier of the intestine (leaky gut syndrome).

Due to increased epithelial permeability, LPS penetrates the systemic bloodstream, causing a state of metabolic endotoxemia. The immune system's response to these toxins triggers systemic chronic inflammation, which directly damages cell receptors, provoking the development of insulin resistance (IR) and diabetes.

3. Bile acid theory

Bile acids are produced in the liver and play an important role in the absorption of fats. However, intestinal bacteria transform them into secondary bile acids, which act as powerful signaling molecules in the regulation of energy metabolism. The normal microbiome supports the generation of these acids, which suppress excessive inflammation. Accordingly, in dysbiosis, the formation of secondary bile acids is reduced, which entails impaired glucose metabolism and contributes to the occurrence of DM-2.

Personalized microbiome correction: the diabetes treatment of the future

Since each microbiome is unique, universal diets often do not bring the expected result. Modern 4P medicine (personalized, predictive, preventive, participatory) offers a fundamentally new approach: treating DM-2 through targeted correction of the intestinal microbiota .

Clinical trials in women with type 2 diabetes have demonstrated the efficacy of personalized nutrition and pharmabiotics. Patients received an individually designed diet based on their microbiome profile, which included specific biologically active substances (BAS) and specific probiotic strains (e.g., L. casei and L. plantarum ).

After a course of personalized therapy, patients experienced statistically significant decreases in fasting glucose, creatinine, urea, triglycerides, very low-density lipoproteins, and inflammatory markers (such as tumor necrosis factor-alpha — TNF-α). At the same time, the microbiome restored its normality: the number of opportunistic microorganisms, in particular Enterococcus faecalis , pathogenic E. coli ( E. coli ), Pseudomonas aeruginosa , and Candida fungi , significantly decreased, and the population of beneficial Lactobacillus significantly increased .

Conclusions

The gut microbiome is a fundamental "organ" that directly affects glucose metabolism and the development of type 2 diabetes. Chronic inflammation, insulin resistance, and metabolic endotoxemia originate in the gut due to bacterial imbalance. Abandoning universal protocols in favor of personalized medicine (microbiome analysis followed by targeted pharmabiotics and prebiotic diet) allows not only to relieve the symptoms of diabetes, but also to break the pathological chain at the physiological level, stabilizing sugar levels and restoring a person's metabolic health.

Short questions and answers on the topic (Q&A)

1. How exactly do gut bacteria affect blood sugar levels?

Answer: Beneficial bacteria digest dietary fiber, releasing specific substances called short-chain fatty acids (especially butyrate and propionate). These acids act as hormone-like signals: they reduce inflammation, protect the intestinal lining, and directly increase the sensitivity of the body's cells to insulin, which allows the body to lower glucose levels more effectively.

2. What bacteria are most lacking in people with type 2 diabetes?

Answer: In type 2 diabetes, dysbiosis occurs, during which the number of beneficial Bifidobacterium and Lactobacillus drops sharply . But most importantly, butyric acid (butyrate)-producing bacteria, such as Faecalibacterium prausnitzii and Roseburia intestinalis , as well as the bacterium Akkermansia muciniphila , which protects the intestinal mucosal barrier, disappear.

3. What is "metabolic endotoxemia" and how does it provoke insulin resistance?

Answer: Harmful (gram-negative) bacteria contain toxins called lipopolysaccharides (LPS). When the intestinal wall becomes inflamed and permeable due to poor nutrition ("leaky gut"), these toxins leak into the bloodstream. The immune system responds to them with chronic systemic inflammation, which "blinds" cells, making them resistant to insulin (insulin resistance).

4. Can I normalize my sugar levels with probiotics or diet?

Answer: Yes, but only with an individual approach. Studies show that standard probiotics often do not work effectively, but the use of a personalized diet together with specially selected bacteria (pharmabiotics) based on microbiome analysis leads to a significant reduction in glucose and cholesterol levels and the restoration of normal metabolism.