What is Type 5 diabetes? New form of disease recognised after decades of debate

A new type of diabetes that’s linked not to obesity but to malnutrition has been officially recognised, decades after it was first observed in developing countries.

The International Diabetes Federation (IDF) this month officially recognised the disease as “Type 5 diabetes”, and set up a working group to develop new guidance for doctors on how to spot it.

The rare form of diabetes is believed to affect about 25 million people globally, and is caused by malnutrition-induced low insulin production among lean and malnourished teenagers and young adults in low and middle-income households, according to reports.

The new disease, distinct from Type 1 and 2 diabetes, was officially recognised through a vote on 8 April at the IDF’s World Diabetes Congress in Bangkok, Thailand following years of debate over its identification.

Meredith Hawkins, professor of medicine at Albert Einstein College of Medicine, said malnutrition-related diabetes “has historically been vastly underdiagnosed and poorly understood”.

“The IDF’s recognition of it as ‘Type 5 diabetes’ is an important step toward raising awareness of a health problem that is so devastating to so many people.”

Type 5 diabetes is a rare form of the disease that in the past has often been misdiagnosed as either Type 2 diabetes – which can be influenced by lifestyle choices and relates to the body’s inability to use the insulin it produces – or Type 1 diabetes, an autoimmune condition resulting in the destruction of insulin-producing cells.

Nihal Thomas, professor of endocrinology at Christian Medical College in India and a member of the Type 5 Diabetes Working Group, said the disease causes pancreatic beta cells to function abnormally, which leads to insufficient production of insulin. “Due to the lack of formal recognition, this condition has been understudied and misdiagnosed,” he was quoted by The Indian Express as saying.

Patients are often misdiagnosed as having Type 1 diabetes despite the fact that providing them too much insulin can rapidly prove fatal, Dr Hawkins told Medscape Medical News.

“Malnutrition-related diabetes is more common than tuberculosis and nearly as common as HIV/AIDS, but the lack of an official name has hindered efforts to diagnose patients or find effective therapies,” Dr Hawkins said.

Dr Hawkins said she first learned of malnutrition-related diabetes in 2005 while teaching at global health meeting, when doctors from multiple countries told her they were seeing patients with “an unusual form of diabetes”.

“The patients were young and thin, which suggested that they had Type 1 diabetes, which can be managed with insulin injections to regulate blood sugar levels. But insulin didn’t help these patients and in some cases caused dangerously low blood sugar,” she said.

The patients did not seem to have Type 2 diabetes either, with is typically associated with obesity, she said, adding: “It was very confusing.”

Dr Hawkins founded Einstein’s Global Diabetes Institute in 2010, which began leading international efforts to uncover the underlying metabolic defects that leads to malnutrition-related diabetes. More than a decade later in 2022, Dr Hawkins and her colleagues at the Christian Medical College demonstrated that this form of diabetes was fundamentally different from Type 1 and 2.

She said people with this form of diabetes have a profound defect in the capacity to secrete insulin, which wasn’t recognised before. “This finding has revolutionised how we think about this condition and how we should treat it.”

Doctors worldwide are still unsure how to treat these patients, who often don’t live for more than a year after diagnosis, according to Dr Hawkins.