Type 1 Diabetes: Age of Onset

In adults, type 1 diabetes can develop slowly because the immune system’s attack on the pancreatic cells that produce insulin is also slower. It might require further testing and resemble type 2 diabetes for months or years.

People who develop an especially slow-developing form of insulin-reliant diabetes called latent autoimmune diabetes in adults (LADA), sometimes called type 1.5 diabetes, may wait years before receiving a proper diagnosis.

“Unfortunately, it’s easy for these people to be misdiagnosed with type 2 because of how slowly LADA develops,” Bogdanovics says. “This refers directly to how much slower the attack on the pancreatic cells is compared to the rate of attack in children.”

Michael Fang, PhD, an assistant professor at Johns Hopkins University’s Bloomberg School of Public Health, says he believes that many doctors are unaware of how frequently type 1 diabetes develops in adulthood, potentially leading to misdiagnosis and suboptimal treatment.

“I think one big contributor is the misconception that type 1 diabetes is a childhood disease,” Dr. Fang says. “As a result of this, providers may assume that all adult patients have type 2 diabetes, even if they do not fit the ‘classic’ clinical picture of a type 2 diabetes patient.”

“Guidelines currently recommend that providers test for autoantibodies when they suspect an adult patient ‘may’ have type 1 diabetes,” Fang says. “I suspect this isn’t performed very often, partly because of the lack of awareness that type 1 diabetes can occur in adults.”

• C-peptide test: This measures the amount of insulin your body is producing. In type 1 diabetes, C-peptide is low; it is traditionally high in type 2 diabetes.
• Autoantibody test: Autoantibodies, or malfunctioning proteins, indicate that the immune system is attacking and destroying the cells in your pancreas that produce insulin.