Is Type 1 Diabetes Caused By Genetic Or Environmental Factors?

Overview 

Diabetes is a long-life metabolic disorder, the prevalence of diabetes has been increasing over the past few decades across the globe. According to WHO, about 5 to 10% of the world population has been affected by Type 1 Diabetes and the rate of prevalence is increasing. The reason for its prevalence is not known. However, studies suggested that it is the interaction between genetic and environmental factors. If you are living with T1D or not and wonder how it develops, this article covers the potential cause of T1D.^1,2

What is type 1 diabetes?

Type 1 Diabetes is a chronic condition in which the body's immune system attacks the production of insulin-producing beta cells which results in less or no insulin production, with insulin glucose staying in the blood and leading to high sugar levels. It affects the different parts of the body and causes problems to the kidneys, liver, eyes, blood vessels, Heart, and feet. It is also known as juvenile or insulin-dependent diabetes.³ 

Symptoms of type1 diabetes

Type 1 diabetes symptoms have early onset. 

Figure: Common Symptoms of Type 1 Diabetes 

Created by Aastha Malik

If diabetes is not properly managed, it may develop certain complications:

• Kidney diseases
• Neuropathy
• Heart problems
• Atherosclerosis
• Diabetic retinopathy
• Amputation etc ⁴

Type 1 Diabetes is caused by an autoimmune reaction 

Yes, it is an autoimmune disease. Several factors including genetics or environment trigger the immune system, which mistakenly recognizes the beta cell as an invader and develops autoantibodies and damages beta cells in the pancreas. The reason for this auto reaction is not fully defined, however, this destruction cause release of additional antigen which further activate the T lymphocytes, it is generally called T cell-mediated disease.⁵

Is Type 1 diabetes caused by genetic or environmental factors?

Type 1 diabetes is attributed to both genetic and environmental factors that trigger the autoimmune reaction. Studies suggest that genes play an important role in the prevalence of diabetes, however, about 10-15% of individuals develop TD1 with genetic risk. Other environmental factors include an unhealthy diet, polluted environment, exposure to chemicals, nutrition deficiencies, infections, and stressful routines that have a significant impact on developing TD1.⁶ 

What is autoimmunity?

Autoimmunity is defined as the response of the immune system in which the body fails to recognize its own components called autoantigens and develops antibodies against it, these antibodies are made of B lymphocytes or T lymphocytes.

Autoimmunity is the loss of self-tolerance in the immune system which activates the lymphocytes against self-antigen and develops an autoimmune reaction.

Autoimmunity is affecting different parts of the body including muscles, joints, digestive tract, endocrine system, etc. It is responsible for developing conditions including Type 1 diabetes, rheumatoid arthritis, Grave disease, etc

Factors that contribute to the development of autoimmune reaction in T1D are categorized into genetic or environmental factors:

Genetic Factors: 

Studies suggested that genetic factors play an important role in autoimmune disease.

• Family history of autoimmune disease: 1 in 17 children is at risk of developing T1D.
• Specific Ethnic Population: e.g White people have the highest rate to develop T1D.
• Genetic mutation of HLA(Human Leukocytes Antigen) present on chromosome 6, cell protein that is responsible to differentiate between body and foreign cell components.

Environmental Factor:

Certain environmental factors trigger the auto-immune reaction by interfering with the normal functioning of the immune system.

• Exposure to toxic chemicals. eg Pesticides, Ultraviolet Rays, Smoking, etc
• Infections e.g E.coli, Scarlet Fever, etc
• Unhealthy diet, food that contains chemicals such as glycotoxin, etc
• Stressful routine or trauma

When immune cells attack the pancreas

In Type 1 Diabetes when immune cell T lymphocytes attack the beta cells in the pancreas which are responsible for the production and secretion of Insulin. When Beta cell is under attack it directly affects the production of insulin and creates difficulty in maintaining sugar level in the blood.

Factors  that can affect the production of the beta cell are:

• Autoimmunity
• Hyperglycemia
• Inflammatory reactions
• Lipotoxicity
• Insulin Resistance.⁷ 

The role of insulin in regulating blood sugar

Insulin belongs to the group of peptide hormones secreted by the pancreas that helps to maintain a steady condition in the body by signaling to the liver, muscles, and fat cells. Insulin has two roles:

a) Maintaining blood sugar level in the body: Food in the form of carbohydrates converts into glucose and enters the blood which becomes the source of energy in the body.

b)Maintain the energy level by storage of excess glucose amount in the form of glycogen, which helps to sustain the blood sugar levels.⁸

What happens when you don’t have enough insulin in your blood?

When the body doesn't have enough insulin in the blood due to a) less production of beta cells b)not making enough insulin c)Insulin Resistance.

• As a result, the body absorbs glucose which is the source of energy. Normally the liver releases glycogen to maintain the blood sugar level but in Type 1 Diabetes liver releases ketone as an alternative energy source high levels of ketones might develop a condition called ketoacidosis.

• Unabsorbed glucose burdens the kidney with excess glucose filtration, this excess glucose is excreted into the urine, and glucose retains more water and increases the urine flow which ultimately results in a dehydrated body. Urinary incontinence is a symptom of both Type 1 and Type 2 Diabetes.^9,10 

Conclusion

Type 1 diabetes has a major impact on your daily lifestyle which requires proper management. Type 1 Diabetes is an autoimmune reaction that destroys the beta cell and affects insulin production. Autoimmune reactions are triggered by the interaction of genetic or environmental factors. Insulin is important to regulate body sugar levels and its deficiency impaired normal body function. Maintenance of insulin levels in the body and a balanced lifestyle is required to avoid any complications.