Introduction
The gut microbiota is linked with metabolic syndrome, obesity, and the onset of type 2 diabetes mellitus due to decreased insulin resistance and glucose intolerance. Serious health complications can occur due to uncontrollable diabetes mellitus, including blindness, impaired kidney function, lower limb amputation, or myocardial infarction.
Though various treatment options are available, the increase in diabetes and associated complications is at its peak. Therefore, researchers have started a new approach to treating the condition that mainly focuses on remodeling the gut microbiome with prebiotics, probiotics, fecal microbial transplantation, and synbiotics.
The new treatment approach was initiated due to differences in gut microbiome composition in preclinical animal models and patients with type 2 diabetes mellitus and its complications, such as diabetic retinopathy, diabetic nephropathy, diabetic neuropathy, cardiovascular disease, and cerebrovascular disease. The article gives an overview of gut health and its relationship to diabetes in humans.
What Is Diabetes?
It is a group of diseases that occur due to high sugar levels in the blood. This mainly occurs due to decreased insulin sensitivity or pancreatic insulin production in the tissues. Various environmental and genetic factors cause both type 1 and type 2 diabetes.
Type 1 Diabetes: The pancreas does not make insulin because the body’s immune system attacks pancreatic cells.
Type 2 Diabetes: The pancreas makes less insulin than required and thus, the body becomes insulin resistant.
What Is a Gut Microbiome?
The gut microbiome comprises various bacteria, fungi, viruses, and their genes that live inside the digestive tract of human and animal bodies. The gut microbiome plays an important role in human health and wellness.
How Is Gut Health Linked to Diabetes Reversal?
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The gut microbiome comprises various microorganisms, including trillions of species of bacteria, viruses, protists, and fungi. Dysbiosis or imbalance in these gut microbiota components can cause dysfunction in the body and various pathologies. These include neuronal, cardiovascular, metabolic, and immune disorders caused by insulin resistance, bile acid metabolism, inflammatory status, and incretin secretion. This further leads to the initiation of type 2 diabetes, obesity, and metabolic syndrome due to insulin sensitivity and glucose intolerance.
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Some studies have shown a significant connection between the development of diabetes and changes in the gut microbiome composition. On the other hand, some bacteria have been shown to reduce the risk of diabetes by exerting a positive role, such as maintaining barrier integrity in the intestines and reducing proinflammatory markers. Various bacteria, such as Roseburia intestinalis, Lactobacillus fermentum, and Accermansia muciniphilia have suppressed proinflammatory cytokines and improved insulin sensitivity and glucose metabolism.
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In addition, some drugs used to treat diabetes, such as metformin, have also been found to interfere with gut microbiome composition through glucose homeostasis, modulation of inflammation, and gut permeability. Also, in some cases, metformin promotes propionate and butyrate production in patients with diabetes-associated gut microbiome imbalances and thus improves the patient's ability to catabolize amino acids.
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Therefore, all these changes, along with an increase in the microorganism Accermansia in the human gut, may enhance the effects of metformin on glucose metabolism. Also, the metabolic factors linked with oxidative stress and chronic low-grade inflammation provide a link between gut microbiome imbalance and diabetes, along with how they also influence the onset and complications associated with diabetes.
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This relationship between the gut microbiome and diabetes has provided a basis for the concept that the modulation of the gut microbiome can reverse diabetes and be a new strategy for managing diabetes and its associated complications.
What Is the Link Between the Gut Microbiome and Diabetic Complications?
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Gut Microbiome and Diabetic Nephropathy - This diabetic complication usually occurs in about 40 percent of people with poorly managed diabetes, and about 20 percent are hemodialysis patients. Although, complication can arise due to various other reasons, such as lifestyle risks, societal habits linked with hypertension and diabetes, and the progression of the condition due to high blood pressure, genetics, age, and obesity.
Recently, diabetic nephropathy has been linked with a gut microbiome imbalance, or dysbiosis, due to its role in the onset of chronic kidney disease. Therefore, studies have suggested that balancing the gut microbiome and dysbiosis could help manage the condition. Thus, various probiotics and synbiotics are used to modulate the gut microbiome in patients with diabetic nephropathy.
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Gut Microbiome and Diabetic Neuropathy - A neurodegenerative nutritional disease, diabetic neuropathy occurs due to chronic uncontrolled diabetes, which causes numbness and peripheral nerve damage. The condition is linked to changes in the gut microbiome diversity and has shown an increase in the pathogen population, suggesting insulin resistance in diabetic neuropathy. Therefore, it is believed that modulation of gut microflora can lead to an improvement in insulin resistance. However, there is no pharmacological intervention for treating diabetic neuropathy, and further investigation is needed to study the effects of synbiotics and probiotics in controlling or treating diabetic neuropathy.
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Gut Microbiome and Diabetic Retinopathy - The condition occurs due to poorly managed diabetes, which causes an increase in eye pressure and further build-up of glucose in the eye's blood vessels. This process usually occurs in various complications of the eyes, such as glaucoma, cataracts, and retinopathy.
Recently, the gut microbiome has also been linked with the development of diabetic retinopathy. The microflora is present in different proportions throughout the body, including the eye. Studies have also shown a link between the gut microbiome and the microflora on the ocular surface of the eye and the development of various eye diseases. Also, microbiome levels were decreased in humans with diabetic retinopathy compared to normal, healthy individuals.
Although the modulation of the microbiome with the administration of probiotics has shown significantly positive effects in pre-clinical trials, it also supports the concept of gut microbiome modulation in association with diabetic retinopathy. However, no specific studies have investigated its effects on microbiome modulation in humans with diabetic retinopathy. Therefore, further investigation is still needed to clarify the doubts about probiotics and synbiotics.
Conclusion
Diabetes and its various complications have been linked to an imbalance in the gut microbiome in multiple studies. Though the pre-clinical studies of this concept are quite satisfactory, the results are not promising enough to be relevant when various parameters of diabetes are studied in various clinical trials. Therefore, gut microbiome modulation with the help of synbiotics and probiotics may significantly affect controlling and managing diabetes. However, researchers need to conduct further studies involving human samples for establishing the link between gut health and diabetes reversal high.
