As a response to several different factors, some individuals with type 1 diabetes can also develop characteristics of type 2 diabetes. Find out what may put you at risk and how you can try to prevent and manage ‘double diabetes.’

While people are not diagnosed with both type 1 and type 2 diabetes at the same time, those with type 1 may be at risk for also developing characteristics of type 2 diabetes over time.

Type 1 diabetes is an autoimmune condition in which the body no longer produces insulin. With type 2 diabetes, the body can still produce some, but not enough, insulin, and the body cannot use the insulin it makes efficiently. This leads to chronic high blood glucose levels. ‘Insulin resistance’ is the term used to describe when the body becomes less and less efficient at using insulin.

While the two conditions are fundamentally different, people with type 1 can still develop the inability to use prescribed insulin efficiently, mirroring some of the symptoms seen in those with type 2. This often happens because of a condition called metabolic syndrome. The term ‘metabolic syndrome’ refers to a group of conditions that often occur together, including:

High blood pressure
Excess weight or obesity (specifically excess fat around the waist)
High blood glucose
Abnormal cholesterol levels
High fat levels in the blood

People who have a combination of some or all of these conditions are said to have metabolic syndrome. Having metabolic syndrome increases a person’s risk for heart disease and type 2 diabetes. Studies suggest that a majority of people with type 2 diabetes have metabolic syndrome. And while metabolic syndrome increases the risk of type 2 diabetes, people with type 1 can still have it, which can lead to insulin resistance and other characteristics of type 2.

This phenomenon is sometimes referred to as “double diabetes,” though some experts have suggested a more accurate phrase would be “people with type 1 diabetes who also have type 2 characteristics.”

“Those of us in the field want people to know that even if you have type 1, you can develop metabolic syndrome, so you need to be assessed for cardiovascular risk,” said Dr. Anne Peters, an endocrinologist and professor of clinical medicine at the University of Southern California, Keck School of Medicine. “[Double diabetes] is a shorthand for clinicians, but the key is that it shows up as people with type 1 who have metabolic syndrome.” Peters clarified that while she looks to reduce cardiovascular risk in everyone, treatment is especially important for people with metabolic syndrome.

How prevalent is ‘double diabetes?’

In a recent study aimed at exploring the prevalence of diabetes, out of 107 participants with type 1 diabetes, 57 of them could be classified as having excess weight or obesity based on their BMI, and 62 of them met the definition of having “double diabetes.” Those who had “double diabetes” were more likely to be older, have had diabetes for a longer time, have a higher A1C, and have abnormal lipids.

Which risk factors can lead to ‘double diabetes?’

The factors that place people with type 1 at a higher risk for developing double diabetes are in many ways similar to the risk factors for developing type 2 alone. According to this study in people with type 1, excess weight or obesity, a sedentary lifestyle, intensive insulin therapy, and being in a high-risk ethnic group may all contribute to the risk for double diabetes.

“The most common feature of metabolic syndrome is excess weight, and two thirds of people with type 1 are either overweight or obese,” added Peters. “By the time they reach a certain age in their 60s, about two thirds will also have [high blood pressure]. Also, just because you have type 1 does not mean you don’t have type 2 genes,” she said, explaining that those with type 1 who have a family history of type 2 are also at a higher risk level.

Contributing to these risk factors is the concerning fact that the number of people with type 1 diabetes and excess weight or obesity is increasing. In one study, which monitored a large group of people with type 1 diabetes over a period of two decades, the number of people who had excess weight increased by nearly 50%, while the number of people with obesity increased seven-fold.

Researchers have established that insulin therapy can cause weight gain. This can create a vicious cycle where insulin therapy leads to weight gain, which both contribute to insulin resistance, which can lead back to an increase in insulin dosing. In fact, one of the signs of double diabetes in people with type 1 may be the need for more and more insulin to meet glucose targets. This is why early on, weight management, along with glucose management, are crucial for people with type 1 to prevent insulin resistance.

What can you do to prevent or manage ‘double diabetes?’

There are ways to minimize the risk of developing double diabetes.

Lifestyle changes such as improving your diet and getting plenty of exercise can help you manage your weight and can help make the insulin you take work more efficiently.

As a general guideline, the American Diabetes Association recommends getting 30 minutes of aerobic exercise on most days of the week. Aerobic exercises include activities like walking, running, cycling, or swimming. Additionally, eating foods that are low-carb or high in nutrients like fiber and healthy fats can help you manage your weight and decrease insulin resistance.

In addition, your healthcare provider may consider using medications that are only indicated for people with type 2 diabetes, such as metformin, GLP-1 receptor agonists, or SGLT-2 inhibitors.

“I mainly focus on weight loss, so I use GLP-1s, but I also prescribe metformin,” said Peters. “I focus on weight and exercise to bring down insulin resistance because many of these people have a much higher insulin resistance than others with type 1. I am also more likely to start a statin [a cholesterol-lowering medication] at a younger age.”

While metformin can help decrease insulin resistance directly, GLP-1 receptor agonists and SGLT-2 inhibitors can also help lower glucose levels and protect against complications like heart and kidney disease. GLP-1 receptor agonists can also be used for weight management and for treating obesity. These drugs are not indicated for people with type 1 diabetes, however, so talk with your healthcare team to see if these options are safe and available to you. For instance, taking SGLT-2 inhibitors has been shown to increase the risk of diabetic ketoacidosis (DKA) if you have type 1.

According to Peters, double diabetes comes down to three key factors: weight, lipids, and blood pressure. “I aim to treat each of these factors, bring down insulin resistance as much as possible, and continue to treat the type 1 diabetes, because that’s still there,” she said.

Keep in mind that insulin resistance, along with excess weight and obesity, is not specific to those with type 2 diabetes. Understanding how these things can affect your health is important for managing your glucose levels and preventing complications.

“I’ve always been a believer that anybody, with or without diabetes, with or without metabolic syndrome, needs to maintain their weight and exercise,” said Peters. “Maintaining insulin sensitivity, to me, is a sign of health no matter who you are. All of us are at a higher risk for these health issues as we get older, so keep fit!”

Here are some additional helpful resources:

Obesity and Diabetes: Causes, Treatments, and Stigma
It’s Not Just Blood Sugar, High Blood Pressure Matters Too
What’s Cholesterol and Why is it Important?
Strategies for healthy eating
Which Type of Exercise Is Best for Managing Diabetes, Aerobic Exercise or Weightlifting?