Let's Talk About the Causes of Diabetes

There are a lot of myths and misconceptions about this disease, including where it comes from, who gets it, and why. Let’s take a closer look.

by Sunny Sea Gold Health Writer

For such a common disease, the roots of diabetes are surprisingly misunderstood. For instance, you can’t just “give it to yourself,” as some people suggest—although within certain types of diabetes, specific factors like diet and weight can raise or lower your odds. Understanding the underlying causes and risk factors of diabetes is the first step to keeping yourself healthy.

Diabetes Causes

Our Pro Panel

We went to some of the nation’s top experts in diabetes to bring you the most up-to-date information possible.

Nilem Patel M.D, headshot.

Nilem Patel, M.D.


Adventist Health White Memorial Hospital

Los Angeles, CA

Stelios Mantis, M.D.

Stelios Mantis, M.D.

Pediatric Endocrinologist

Rush University Medical Center

Chicago, IL

Katherine Araque, M.D.

Katherine Araque, M.D.

Director of Endocrinology

Pacific Neuroscience Institute at Providence Saint John’s Health Center

Santa Monica, CA

Diabetes Causes
Frequently Asked Questions
Is diabetes hereditary?

Like many chronic illnesses, your genes can make you more susceptible to developing type 2 diabetes. But having a family history of the illness doesn’t automatically mean you’ll get it. A healthful diet and exercise can lower your risk for the disease.

How can I prevent diabetes?

Unfortunately, Type 1 diabetes isn’t preventable. With type 2 and gestational diabetes, though, you can decrease your odds of getting the disease by reducing the amount of high-sugar foods in your diet, following a consistent exercise routine, and not smoking.

I’m 30 years old. Can I stop worrying about getting diabetes?

Unfortunately, no. You might be thinking about “juvenile diabetes,” a name often used for type 1 diabetes that typically develops in childhood. But it can be diagnosed well into your 30s. And type 2 diabetes can be developed at any age—in fact, it’s more common after age 45.

Does eating sugar cause diabetes?

No, not directly. But it makes sense that if diabetes is caused by an excess of sugar in your blood, it’s not the greatest idea to consume a ton of high-sugar foods, since this will only raise your blood sugar levels. Also, limit yourself to two alcoholic drinks a day if you’re a guy or one a day if you’re a woman, since these beverages are also high in sugar.

What Is Diabetes, Exactly?

Diabetes mellitus is a group of disorders that causes people to have higher-than-normal levels of sugar—or, glucose—in their blood.

Glucose isn’t inherently bad: It plays an important role in the body’s day-to-day activities, serving as the primary means of energy for your brain, heart, muscle cells, and most everything else. But when there’s too much of it in your blood, or if your cells are unable to tap into it for fuel, you start to have problems.

Here’s how glucose works if the body is functioning properly:

  • During digestion, the food you eat is broken down into glucose (among other things), which then enters the bloodstream.

  • In response, your pancreas releases insulin, a hormone that helps the glucose get out of your blood and into your fat and muscle cells.

  • The cells use glucose for energy to perform their daily functions.

But if you have diabetes, for various reasons, the glucose struggles to get out of your blood and into your cells. As time goes on, extra sugar in the blood causes inflammation and other health troubles.

There are three main types of diabetes—type 1, type 2, and gestational:

Type 1 diabetes is mostly an autoimmune disorder in which your own immune system attacks and destroys insulin-making cells in the pancreas. People with type 1 are no longer able to make their own insulin and must take it (usually as an injection) daily.

Type 2 diabetes is the most prevalent form of the disease. It is not an autoimmune disorder and the pancreas still makes plenty of insulin. However, your body may not use it as efficiently, requiring more and more insulin to help convert glucose into energy. Eventually, the pancreas can’t keep up and blood sugar rises.

Gestational diabetes is similar to type 2 in that the pancreas still makes insulin but your body doesn’t use it efficiently. This type of diabetes is temporary and only happens during pregnancy.

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So, What Causes Diabetes?

There is no one single factor that determines if you'll get any of these three types of diabetes. Multiple variables can affect blood sugar levels and lead to the development of the disease. Let’s take a look at some of those variables and the roles they play.

Family History

There is a hereditary component to all three main types of diabetes.

Several genes and mutations have been pinpointed as increasing the risk of developing type 1. In particular, mutations of a class of genes known as human leukocyte antigen (HLA) genes raise the risk of autoimmune conditions like type 1 diabetes.

Some studies suggest that if your sibling or parent has type 1 diabetes, your risk of getting the disease is 15 times higher than someone without any family history. And if other autoimmune conditions run in your family, your odds of developing one (including type 1 diabetes) also rises.

As for type 2 and gestational diabetes, there are no particular genes to test for, but if either disease runs in your family, you are at a much higher risk of developing it, too.

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Your race, ethnicity, and even geographic location can affect your risk of developing diabetes. Caucasian people, especially of Northern European ancestry, have a higher risk of type 1 than other ethnicities.

Type 1 diabetes also gets more common the further away a person lives from the equator. For instance, people who live in Scandinavian countries have a much higher risk of being diagnosed with the disease.

When it comes to type 2, African Americans, Hawaiians, Latinos, Native Americans, Native Alaskans, and Pacific Islanders are more likely to develop the disease than other ethnicities.


While your odds of getting type 1 diabetes diminish as you exit childhood, your risk of developing type 2 diabetes goes up the older you get.

Technically, you can develop type 2 diabetes at any age, but research shows it becomes much more common after age 45, possibly because of something called “insulin resistance.”

Insulin resistance, wwhen the liver, muscle, adipose and other cells start to respond more slowly or weakly to insulin than they used to, increases as you get older. Type 2 often starts with insulin resistance.


If you smoke, your risk for type 2 diabetes rises by 30% to 40% compared to a nonsmoker. And the more cigarettes you smoke, the higher your risk. Cigarette smoke causes oxidative stress—a type of damage to your cells—as well as inflammation, both of which are linked with diabetes.


While the number on the scale doesn’t determine whether someone will develop diabetes, it is clear that higher levels of body fat increase insulin resistance, raising your risk for type 2 and gestational diabetes. Still, a high body mass index (BMI) doesn’t automatically mean you’ll get diabetes, and a low BMI doesn’t guarantee you’re protected. Anyone of any size can develop type 1, type 2, or gestational diabetes.


Moderate drinking, which means two alcoholic beverages a day for men and one for women (and men over age 65), is linked to a lower risk of diabetes. More than that, though, and your risk goes up. A likely reason: Large amounts of alcohol inflame the pancreas, interfering with its ability to make insulin. It also causes a spike in blood sugar levels.

Lack of Exercise

Sitting all day at a desk job makes your cells less sensitive to insulin, which leads to insulin resistance and increased risk of type 2 diabetes. Take a walk around the block, use the stairs, or bike to work: Any type of exercise makes your cells more sensitive to insulin, allowing glucose to be used more easily for fuel.

High-Sugar Diet

It stands to reason that if high blood sugar is at the heart of the disease, adding more from your diet isn’t going to help matters. Not surprisingly, research shows that sugar-sweetened drinks like soda and fruit juice are linked with an increased risk of developing type 2 diabetes, even if they don’t cause a person to put on weight.

What to Know About Diabetes and Pregnancy

While your odds of developing gestational diabetes rise if you have a genetic predisposition, it can develop in women without any family history as well. Doctors suspect the disease may be triggered by hormonal changes that happen during pregnancy. Most pregnant women are screened for it with a glucose tolerance test during their second trimester.

If you do develop gestational diabetes, the condition is usuallytreated with exercise and diet changes (such as eating less starch and more veggies, fruits, and protein). Most of the time, blood sugar levels go back to normal once the baby is born but having the condition during pregnancy raises your risk for developing type 2 later in life.

Can Other Illnesses Cause Diabetes?

Having another illness can raise your risk for diabetes. In fact, doctors believe that in many cases, a toxin or virus triggers the development of type 1 diabetes in someone with a genetic predisposition. The “invader” kicks the immune system into gear, which then mistakenly begins to attack the pancreas and kill off the insulin-producing beta cells.

As for type 2, there are several underlying conditions that can boost the risk, including polycystic ovary syndrome and Cushing’s disease.

While doctors don’t believe there is a single cause for diabetes, many of the factors that contribute to your risk of type 2 are within your control to manage—especially what you eat and how you exercise. Sure, you could follow a healthy diet and work out every day and still get type 2 diabetes. But your odds are way less than if you sit on the couch snacking on potato chips. Give your health a head start by making the smart choice!

Sunny Sea Gold
Meet Our Writer
Sunny Sea Gold

Sunny is a health journalist with deep expertise in women's and children’s health who has written for some of the largest and most well-known print and digital publications in the United States. She’s also the author of the book Food: The Good Girl’s Drug, and writes essays and reported pieces on body image, eating disorders, parenthood, and mental health. She lives in Portland, OR, with her husband and two daughters.