What Triggers Type 1 Diabetes?

While it has long been known that type 1 diabetes runs in families, experts are less certain about what actually starts the autoimmune attack that defines the disease. Most people with type 1 diabetes have no family history of the condition, and researchers have long speculated that some external triggers, such as viruses, pollutants, or food ingredients, may set off the condition’s progression.

Type 1 diabetes is a genetic, autoimmune condition in which the body’s immune system mistakenly attacks and destroys the cells in the pancreas that produce insulin. Without insulin, the body can’t regulate blood sugar levels, making daily insulin therapy critical for survival.

The exact causes of type 1 diabetes are not always clear. While genetics do play a role, other triggers also may hasten the progression of type 1 diabetes.

Autoimmunity

Autoimmunity is the central cause of type 1 diabetes, though other factors can trigger its progression, says Matthias von Herrath, MD, a San Diego-based consultant for the Diabetes Research Institute in Miami.

Though type 1 diabetes has a reputation for striking suddenly and without warning, it is in fact possible to diagnose type 1 diabetes long before it causes any symptoms. Type 1 diabetes screening can identify the presence of autoantibodies, the markers of an autoimmune attack. If you have two or more autoantibodies for type 1 diabetes, you already have the condition, even if the autoimmune attack hasn’t yet impacted your health.

• Stage 1 You test positive for two or more autoantibodies, but blood glucose levels are normal.
• Stage 2 You test positive for two or more autoantibodies, and blood glucose levels are abnormal but not yet consistently high enough to produce traditional symptoms.
• Stage 3 Blood glucose levels are consistently high, traditional symptoms develop, and the body cannot produce enough insulin on its own to regulate blood sugar.

• Hashimoto's thyroiditis
• Graves’ disease
• Celiac disease
• Autoimmune gastritis
• Rheumatoid arthritis
• Addison’s disease
• Vitiligo

Genetics

Genetics frequently play a role in the development of type 1 diabetes, and the risk of developing it increases if it is inherited from both parents.

• 30 percent if both parents have it
• 3 to 8 percent if your biological father has it
• 1 to 4 percent if your biological mother has it
• 0.4 percent if neither parent has it

“Too often, we see a child diagnosed with type 1 diabetes, and it seems like there is no one else in the family with type 1,” von Herrath says. “But then you start testing the parents or grandparents for autoantibodies and discover they test positive for two or three autoantibodies. It simply never progressed to stage 3 with symptoms and the need for daily insulin therapy.”

Von Herrath also says that at least 10 percent of people diagnosed with type 2 diabetes likely have type 1 diabetes or latent autoimmune diabetes in adults (LADA), a very slow developing form of type 1 diabetes that can be easily mistaken for type 2 diabetes for years.

Environmental Triggers

Researchers have looked at numerous environmental factors as potential causes of type 1 diabetes. Although these factors are not likely to cause type 1 diabetes all by themselves, they are all potential accelerators that could speed the progression of type 1 diabetes.

Potential environmental triggers include:

• COVID-19 This virus, which leads to blood sugar level increases, may unmask type 1 diabetes during its progression. Type 1 diabetes diagnoses increased significantly during the pandemic.

  [8]

• Viral Infections, Such as Human Enteroviruses (HEVs) HEVs such as hand, foot, and mouth disease and myocarditis may stress the autoimmune system and lead to cell destruction and type 1 diabetes progression.

  [9]

• Psychological Stress Stress on a biological mother during pregnancy as well as on a child until age 10 may be a factor in type 1 diabetes development, though more research is needed to determine how and why.

  [10]

• Environmental Toxins or Pollution Exposure to certain chemicals and heavy metals, such as nitrates or arsenic, may be linked to autoimmune diseases and increase type 1 diabetes risk.

  [11]

• Obesity and Childhood Diet “A diet high in processed food and sugar increases a person’s risk of obesity, which is an accelerator for type 1 diabetes because it puts pressure on the immune system,” von Herrath says. High weight gain during early childhood may speed up type 1 diabetes development.

  [10]

• Vitamin D Deficiency or Lack of Sunlight Low vitamin D is associated with type 1 diabetes. Studies have looked at how high doses of vitamin D can extend the “honeymoon phase” shortly after insulin treatment begins, in which the pancreas briefly produces significant amounts of insulin on its own again.

  [12]

• Gut Microbiome People with type 1 diabetes have different gut bacteria than people who do not, von Herrath says. But because gut bacteria do not change often, it can be difficult to pinpoint them as a cause or effect. “It’s the chicken or the egg problem. Which changed first?” von Herrath says.

Though researchers have found correlations between every one of these factors and type 1 diabetes development, none is a “smoking gun,” von Herrath says. How and why people develop the disease is fundamentally a mystery: “In type 1 diabetes, we can identify that you are in stage 1 or stage 2 based on autoantibody testing,” he says. “We can tell you that your system is stressed and at some point you will probably tip to stage 3, but we cannot say when.”

The Takeaway

• Autoimmunity is the central cause of type 1 diabetes, and people with type 1 diabetes are more prone to developing other autoimmune disorders.
• Although type 1 diabetes runs in families, a majority of people with the condition have no family history of it. Experts don’t know why the disease strikes in cases like this, though sometimes there may be a hidden family history of the condition.
• Other factors, such as viruses, childhood diet, and environmental toxins, may trigger the progression of type 1 diabetes, sparking the autoimmune attack that leaves the body unable to produce enough insulin on its own.