Misdiagnosis of Type 1 diabetes remains a major problem, despite advances

Diabetes care has advanced dramatically in the past decade, with new therapies like GLP-1 receptor agonists and improved devices like continuous glucose monitors.

However, one significant problem has proven surprisingly durable: misdiagnosis of Type 1 diabetes (T1D).

Estimates suggest that as many as four in 10 adults over the age of 30 with T1D are misdiagnosed with Type 2 diabetes (T2D). Up to 15% of adults diagnosed with T2D actually have latent autoimmune diabetes in adults (LADA).

Sanjay B. Dixit, M.D., medical director at Quest Diagnostics, said part of the problem comes down to an outdated misnomer.

“Type 1 diabetes is still maybe known as ‘juvenile onset’ diabetes, and type 2 diabetes is known as ‘adult onset,’” said Dixit, an endocrinologist who began his career as a primary care physician.

The “juvenile” moniker reflects the fact that T1D often appears in children and teens; however, the name “juvenile diabetes” is no longer used in medical literature as it obscures the reality that the disease can happen at any age. Even the Juvenile Diabetes Research Foundation has moved away from the “juvenile” language, changing its name last year to “Breakthrough T1D.”

Dixit said specialists like endocrinologists are well aware that T1D can strike at any age, but he said primary care providers that see fewer cases of adult-onset T1D might lean towards a T2D diagnosis based off of the premise that T2D is the adult-onset version.

A decade or so ago, a patient misdiagnosed with T1D would likely be prescribed metformin or another oral medication, which would not solve the problem, Dixit said. In such cases, patients would likely be considered difficult-to-treat cases and would be referred to an endocrinologist.

“At that time, the treatment would be insulin,” he said, “and that's the standard treatment for patients with type 1 diabetes even to this day.”

Thus, despite the faulty original diagnosis, they would eventually end up on the appropriate therapy. Still, such delays could increase the risk for complications such as diabetic ketoacidosis (DKA) and organ damage.

Meanwhile, the treatment landscape for T2D has been changing rapidly in recent years, Dixit noted. Newer therapies like Farxiga (dapagliflozin), Jardiance (empagliflozin), Ozempic (semaglutide), and Mounjaro (tirzepatide) have been linked with dramatic decreases in HbA1c.

Dixit said clinicians treating patients who fail to respond to these newer medications should consider the possibility of a misdiagnosis.

“If (adults) aren't achieving their goals within months, and you don't suspect dietary issues or them just not taking the medication, it is certainly worthwhile to have testing for type 1 diabetes be considered strongly,” he said.

Dixit added that clinicians should also consider T1D testing if the patient is lean.

While T2D treatment has rapidly evolved, Dixit said recent advances have also been made in testing and treating T1D.