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Misdiagnosed with Type 2 Diabetes: Why Adults Should be Screened for Autoantibodies 

“The person who we think has type 1 diabetes (T1D) has completely changed,” explains Mary Vouyiouklis Kellis, MD, an endocrinologist at Cleveland Clinic — a participating clinic in the T1D Exchange Quality Improvement Collaborative (T1DX-QI). With 16 years of endocrinology under her belt, Kellis says she’s seen more cases of adults being misdiagnosed with type 2 diabetes (T2D) than she can count. 

“Historically speaking, we’ve thought of people with T1D as lean and young,” says Kellis. “But when half of America is obese, we cannot let body shape lead to the diagnosis anymore. There has to be further testing.” 

In fact, research points out that more than half of T1D diagnoses are in adulthood — which means the diagnosis of this disease should no longer be thought of as a childhood event. And yet, it’s often mistaken for T2D because most healthcare providers — including primary care providers, emergency room providers, and endocrinologists — follow outdated information. 

For the patient, this can mean months or years of being treated with medications intended for T2D and feelings of frustration and failure when those medications don’t work. Instead, they need insulin. 

Screening for T1D autoantibodies to get an accurate diagnosis or intervene 

Thanks to decades of research, we can now test for the autoantibodies related to T1D, which can develop before the age of five years old — even if the full onset of the disease isn’t until years or decades later. 

While testing for autoantibodies in adult cases should be a new standard step in making a diabetes diagnosis, it should also be considered much sooner — especially in those with children or grandchildren with the disease. 

Identifying T1D before the full onset of the disease (before symptoms develop and the need for daily insulin therapy) presents an opportunity to prevent diabetic ketoacidosis (DKA) and discuss potential options with your healthcare team and leading T1D screening organizations like TrialNet.  

Misdiagnosed even with a family history of T1D  

“I’ve had patients come in so matter-of-fact,” recalls Kellis. “They tell me their son has T1D, or their granddaughter has T1D, but they never questioned their T2D diagnosis. Sometimes, they’re already taking insulin but wondering why their lifestyle efforts are helping.” 

Kellis finds these patients by happenstance when they are referred to her by a primary care who is struggling to help the patient get blood sugars in their target range or when the patient is frustrated and seeks a new endocrinologist.  

“An obese older woman came in to see me,” recalls Kellis. “She told me her son was diagnosed with T1D at 20 years, and she was diagnosed with T2D recently and taking metformin. I screened her for autoantibodies — she was positive.” 

The woman was shocked, as she thought she was much too old to develop T1D. 

“Her blood sugars weren’t extremely high, but her A1c was 8 percent, and she couldn’t get her blood sugars down where she wanted to be,” explains Kellis. Insulin production tends to fade at a much slower rate in those diagnosed in adulthood compared to children.  

When the misdiagnosed patients are already on insulin at the time of diagnosis, it still isn’t usually enough insulin or being prescribed in the same manner if they’d been accurately diagnosed. 

“I had another patient who was 68 years old, taking metformin,” explains Kellis. “Her daughter had T1D. Even though her A1c was in the 7-8 percent range, she still didn’t feel well. Sure enough, she tested positive for autoantibodies. We added long-acting insulin, and she’s feeling so much better.” 

“We need new education for our primary care and endocrinology providers,” stresses Kellis. “You can’t just put someone in a mold because of their body size or age. You cannot assume they have T2D. And testing for autoantibodies is relatively easy to do.” 

Can T1D screening become part of routine care? 

“There isn’t enough time,” says Kellis, pointing to the biggest obstacle in making autoantibody screening part of routine patient care in primary or emergency healthcare.  

“Primary care physicians already have so much to do in those 15-minute visits,” says Kellis. “They’re juggling multiple medical issues, thousands of prescriptions that need to be managed and renewed. It’s very hard to standardize something like T1D screening in such a time-crunched system.” 

Even adding screening education to endocrinology appointments — teaching patients with T1D why they should encourage family members to get screened — is a big ask. 

“It’s hard enough to download all the data from a patient’s continuous glucose monitor and pump, make insulin dosing adjustments, and support them with existing T1D, let alone teach them about screening,” says Kellis of the limited time in endocrinology appointments. 

Ideally, Kellis thinks the most logical approach would be to use the electronic medical records (EMR) system to flag patients with a family history of T1D, then send that patient information via MyChart to educate them about the importance of getting screened. 

“It has to be an automated messaging with good education because there isn’t enough time, and you need to find those patients.” 

“The time crunch is always a big issue in anything we do in healthcare,” stresses Kellis. “When we talk about screening, we need to do it in a way that’s not asking for additional time from the provider while still getting essential information to the patient.” 

Kellis is also hoping the T1DX-QI will develop standardized handouts that could be handed out to patients when there isn’t time for a discussion. Additionally, automatic messages via MyChart could help reinforce the educational materials. 

Making T1D screening an easy blood draw option for providers 

Kellis points out another issue: requesting T1D screening as a provider requires knowledge, and there isn’t an easily accessible T1D panel a provider could order for a blood draw.  

“While there are some ‘Diabetes Autoimmune Panel’ test options to look for some of the autoantibodies associated with type 1, these panels aren’t available in all labs, and it’s not a standardized panel,” explains Kellis. 

Instead, the provider would have to specifically check boxes for different types of autoantibodies or c-peptide levels (the indicator of how much insulin a person produces). This requires in-depth prior knowledge of T1D. 

“If we can work through the T1DX-QI to develop a standardized blood lab panel with the major lab systems, we could make a ‘T1D screening panel’ that automatically looks at the most important test results,” says Kellis. 

Of course, research tells us that 85 to 90 percent of people diagnosed with T1D have no family history of the disease — but getting family members tested would be the easiest first step to standardizing screening. 

Many people still don’t know about interventional therapies (both FDA-approved and others still in clinical trials), adds Kellis, that can delay the full onset of the disease. Without understanding the potential to detect and delay the disease, there may not be much motivation to screen for it. 

In the end, Kellis knows there will be reluctance. 

“It’s kind of like breast cancer screening decades ago — some people didn’t want to know because they don’t want to sit with the anxiety if there’s nothing they can do about it,” says Kellis. “But now, we can do something about T1D. We need people to get screened.” 


LEARN MORE: ALL ABOUT SCREENING FOR T1D