Type 1 vs. Type 2 Diabetes: What Is the Difference?

By: Christine Byrne

Diabetes is a chronic condition affecting many Americans, but there are some important differences between type 1 and type 2 diabetes. Here's what you need to know about symptoms, diagnosis, treatment and management of diabetes.

Photo: Getty Images / LaylaBird

If you live in America, you undoubtedly know someone who lives with diabetes—the Centers for Disease Control and Prevention (CDC) reports that about 1 in 10 Americans has diabetes. Of these roughly 30 million people, only 1.25 million have type 1 diabetes, and the remaining 29 million have type 2 diabetes. While there are similarities between these two types of diabetes, they're actually two distinct conditions, each with unique symptoms and management protocols. Here's what you need to know about the differences (and similarities) between type 1 and type 2 diabetes.

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Both type 1 and type 2 diabetes have to do with the hormone insulin.

Without getting too deep in biochemistry, it's important to know that insulin is a hormone secreted by the pancreas when levels of blood glucose (blood sugar) in the body are high—that is, right after a meal or snack that contains carbohydrates, which are made of glucose and other sugars. In a nutshell, insulin tells your body to shuttle glucose to cells for energy, and to store glucose in the liver and other tissues. When this happens, your blood sugar levels lower, your body gets the energy it needs, and any leftover glucose is stored and saved for when you need energy between meals.

Read more: 12 Healthy Ways to Lower Your Blood Sugar

In type 1 diabetes, your body doesn't produce insulin.

"Type 1 diabetes is due to not producing any insulin," says Grenye O'Malley, M.D., an endocrinologist at the Mount Sinai Diabetes Center and an assistant professor at the Icahn School of Medicine at Mount Sinai. "The most common cause is an autoimmune process in which your body attacks your own pancreas." Without insulin, your body doesn't know to use glucose for energy (or storage), even after you've eaten and there's plenty of glucose in your blood. In fact, your liver ends up releasing more glucose into your blood—because glucose isn't being shuttled to your liver for energy and storage, it thinks you're starving. So, your blood sugar stays high (this is called hyperglycemia), and other cells don't get the energy they need, which can lead to serious health problems.

"Type 1 is typically diagnosed at a younger age, but it can be diagnosed at any age," O'Malley says. Doctors and scientists aren't exactly sure what causes type 1 diabetes, but it's likely a genetic condition, and it isn't caused by diet or other lifestyle factors. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), a patient with type 1 will experience symptoms like increased hunger and thirst, frequent urination, fatigue, blurred vision, numbness or tingling in the hands and feet, sores that don't heal, and unexplained weight loss.

If a patient shows these symptoms, a doctor will likely test glucose using one of three tests: a fasting plasma glucose test, an oral glucose tolerance test or a random plasma glucose test. Glucose levels of 126 or above for the fasting plasma glucose test, or 200 or above for the oral glucose tolerance or random plasma glucose tests, are indicative of diabetes. After diagnosis and with proper management, these symptoms should disappear.

In type 2 diabetes, your body produces insulin, but it doesn't work properly.

"In type 2 diabetes, you produce insulin, but the main issue is that the rest of your body does not listen to it," O'Malley explains. "We call this insulin resistance." When blood sugar is high and insulin is released, your body ignores it. Just like in type 1 diabetes, your blood sugar stays high, your liver releases even more glucose, and other cells don't get the energy they need.

"With time, some patients with type 2 diabetes may start to produce less insulin, but not to the same extent as with type 1," O'Malley says.

Although some people are genetically predisposed to developing type 2 diabetes, lifestyle factors also play a role. According to the NIDDK, a person is more likely to develop type 2 diabetes if they are overweight or obese, have high blood pressure, have high cholesterol or are not physically active. People over the age of 45, or with a history of heart attack or stroke, are also more likely to develop the disease.

Although people with type 2 diabetes sometimes experience the same symptoms as those with type 1 diabetes prior to diagnosis, many have no symptoms at all (learn more about strange symptoms that may be early signs of diabetes). Doctors routinely test for diabetes using blood glucose tests in patients over 45, or patients with two or more other risk factors, according to the NIDDK. As in type 1 diabetes, glucose levels of 126 or above for the fasting plasma glucose test, or 200 or above for the oral glucose tolerance or random plasma glucose tests, are indicative of diabetes.

An important side note here: These blood glucose tests can also be used to diagnose "prediabetes," a precursor to type 2 diabetes that affects more than 80 million Americans. Glucose levels of 100 to 125 for the fasting plasma glucose test, or 140 to 199 for the oral glucose tolerance test, are indicative of prediabetes. If a patient has prediabetes, a doctor will recommend lifestyle changes like healthier eating and maybe weight loss to prevent the onset of type 2 diabetes (learn more about if you're at risk for prediabetes and symptoms to watch out for).

Because of their different causes, the treatment plans for type 1 and type 2 diabetes are also slightly different.

"People with type 1 diabetes need multiple insulin injections a day or a continuous infusion through an insulin pump," O'Malley says. They also need to check their blood sugar regularly, usually by pricking a finger and using a glucose monitor to test a drop of blood. "Type 1 is not yet reversible; people with type 1 diabetes need to be on insulin for the rest of their lives," O'Malley says.

In both type 1 and type 2 diabetes, regular exercise and a balanced diet are also important for keeping blood sugar levels relatively steady, according to the American Diabetes Association. People with diabetes should work with a registered dietitian to find a sustainable way of eating that balances carbohydrate intake throughout the day.

In type 2 diabetes, it's possible for some patients to manage the condition with diet alone, O'Malley says. In fact, type 2 diabetes is sometimes reversible with proper diet and weight maintenance. But, O'Malley says this reversal can be difficult to maintain long-term. "I focus on how to control diabetes, as opposed to reversing it."

Although some people with type 2 diabetes might use insulin injections for treatment (as in type 1 diabetes), this isn't common. Instead, patients are often prescribed medications meant to keep blood sugar levels low and/or improve insulin sensitivity.

In both types of diabetes, O'Malley recommends that patients try to keep their blood pressure and cholesterol in a healthy range, quit smoking, exercise regularly and periodically have their doctor check for abnormalities in major areas affected by diabetes: heart, kidneys, eyes and feet. All of this minimizes the risks of diabetes.

Ultimately, the goal in managing both types of diabetes is to keep blood sugar levels steady over time.

The goal of diabetes treatment—whether through insulin injections, medication or proper diet—is to keep blood sugar levels as steady as possible to minimize potential complications. All people with diabetes should see a doctor for an A1C test two to four times a year, according to the NIDDK. The test results show average blood glucose level over the past three months, and the goal for many people with diabetes is for that level to remain below 7%.

Diabetes is a chronic condition, and both types of diabetes require long-term treatment. But with proper management, patients can lead long, healthy lives.

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