Inside the Complex Link Between Type 1 Diabetes and Genetics

If you have type 1 diabetes, you’ve probably fielded a lot of questions about what the condition is and isn’t—and what actually causes it. Are you simply just born with it? Is type 1 diabetes genetic?

The thing is, when most people think about diabetes, they’re largely referring to type 2 diabetes. And it makes sense, since of the 34.2 million Americans with diabetes, 90% have type 2, and only about 1.6 million have type 1, according to the American Diabetes Association (ADA).

While type 1 only accounts for about 5–10% of people living with diabetes—including folks like singer Nick Jonas and Supreme Court Justice Sonia Sotomayor—there has been a recent uptick in cases. According to a 2020 report from the CDC, there has been about a 30% increase in type 1 diagnoses in the United States, with numbers jumping from 1.25 million to 1.6 million. And rates among Black and Hispanic communities seem to have the sharpest increase.¹

We’ll get into what causes type 1 in a minute (yes, genes are a factor), but first, let’s talk about how type 1 and type 2 diabetes are different.

What’s the difference between type 1 and type 2 diabetes?

While both type 1 and type 2 diabetes occur when the pancreas can’t make enough insulin for what the body needs, this lack of insulin happens for very different reasons.

“Insulin is a hormone that acts on many different organs in the body, helping them to use nutrients like glucose, fats, and proteins,” Laura C. Alonso, M.D., distinguished professor of medicine, chief of the Division of Endocrinology, Diabetes, and Metabolism, and director of the Weill Center for Metabolic Health, tells SELF.

Type 1, which usually starts in childhood and is seen more often in those of European ancestry, is an autoimmune disease. “The body’s immune system kills the insulin-producing beta cells in the pancreas,” Siripoom McKay, M.D., an assistant professor of pediatrics in diabetes and endocrinology at Baylor College of Medicine and medical director of inpatient diabetes at Texas Children’s Hospital, tells SELF. “Losing the majority of beta cells requires insulin therapy to lower glucose levels.”

Simply put, people with type 1 diabetes have to take insulin every day to stay alive. (Which is why having access to affordable insulin is so important).

Type 2 diabetes, on the other hand, results from changes in the body that make it difficult for your pancreas to produce enough insulin, along with your body not using insulin efficiently (that’s called insulin resistance). As the disease progresses, people with type 2 diabetes may also have to take insulin, but there are a number of other medications and lifestyle changes that can help, too, according to the ADA.

In both cases, the lack of insulin getting into the cells in the body is the hallmark of the disease. “When your body doesn’t make enough insulin, sugar builds up in the bloodstream, and over time that can damage your body,” says Dr. Alonso. If high blood sugar is untreated for months or years, it increases the risk of serious health problems like heart attack, stroke, kidney disease, blindness, and even amputations in severe cases.

Is type 1 diabetes genetic?

The short answer is yes: A family history of diabetes matters. In fact more than 40 genetic regions (where genes are located on a chromosome) have been identified that are related to immune function and beta cells (i.e. the insulin gene), Aaron Cox, Ph.D., an instructor of medicine in diabetes, endocrinology, and metabolism at Baylor College of Medicine, tells SELF. This genetic predisposition is coupled with impaired function of the immune system and what’s called a “precipitating event”—anything that could cause beta cell stress like environmental factors (things like a typically “Western diet” and antibiotic use could contribute)² or even an infection. “Ultimately, the immune system recognizes the body’s own proteins as foreign and proceeds to destroy the beta cells from which these ‘foreign’ proteins originate.”

Source: SELF