Adult Patients Could Be Misdiagnosed with Wrong Form of Diabetes

Type 1 Diabetes is as equally prevalent in adulthood as it is in childhood, but it can easily be misdiagnosed in adult patients, according to a new study published in Lancet Diabetes & Endocrinology.

While Type 1 diabetes is often thought of as a disease that begins in childhood, it can present later in life. Health-care professionals including pharmacists should be aware of this late presentation.

"This has always been suspected, but has been very difficult to show in population studies because classification of Type 1 diabetes at older ages is difficult," said Richard Oram, PhD, a study author and Diabetes UK Harry Keen Fellow and Senior Clinical Lecturer at University of Exeter Medical School.

In the study, researchers examined the frequency of type 1 diabetes among those in the UK in the first 60 years of life who had high genetic susceptibility. They found that of all the genetically defined cases of type 1 diabetes, 42% of patients had been diagnosed after the age of 30.

Although diagnosis of type 1 diabetes later in life was common for those who had it, the number diagnosed still only represented 4% of all diabetes cases diagnosed after age 30. This could make it a challenge to correctly identify those who have type 1 diabetes rather than type 2 diabetes.

"The key message is to be aware that Type 1 diabetes occurs throughout life, that it is more difficult to identify and diagnose in adults, and should be considered as a diagnosis," Oram told Drug Topics. "One key sign in people initially diagnosed as Type 2 diabetes, would be that they do not gain good glucose control on multiple tablet treatments and rapidly progress to insulin."

Oram said the biggest challenge for health-care professionals is that Type 2 diabetes is much more common in those diagnosed after age 30-accounting for 96% of all new cases in this latest study-which means that even if patients present with some signs of Type 1 diabetes, such as slim BMI, they are still more likely to have Type 2 diabetes.

"There is no single clinical feature or test that reliably identifies Type 1 diabetes at diagnosis at older age," he said.

According to the results of the study, however, individuals between the ages of 31 and 60 who had type 1 diabetes were more likely to have a lower BMI, were more likely to use insulin after the first year of diagnosis, and were more likely to have diabetic ketoacidosis than those with type 2 diabetes.

Oram said health-care professionals need to be aware that type 1 diabetes can present later in life so they are able to look for signs of a possible misdiagnosis.

"For patients with Type 1 Diabetes misdiagnosed as Type 2, the most likely outcome is that they are inappropriately treated with diet and tablet treatment. The consequences of this will be poor blood glucose control and likely rapid progression through multiple tablet treatments until they finally get insulin treatment," he said. Diet and tablet treatment for type 1 diabetes patients could also leave these patients at risk for diabetic ketoacidosis, he added.