Type 5 Diabetes: A rare condition makes comeback, know symptoms, causes and treatment

A lesser-known form of diabetes, first identified over 75 years ago, is now making a significant comeback in global medical discussions. Now named Type 5 diabetes, this condition was officially recognised earlier this week by Prof Peter Schwarz, president of the International Diabetes Federation, during the World Congress of Diabetes 2025 held in Bangkok. A global task force has also been formed to study its spread and underlying causes.

According to experts, Type 5 diabetes does not fit the common profiles of either Type 1 or Type 2 diabetes. 'People living with Type 5 diabetes are typically underweight, have no family history of diabetes and show symptoms that do not quite match Type 1 or Type 2 diabetes,' said Dr Nihal Thomas, professor of the department of endocrinology at Christian Medical College Vellore (CMC), who is also part of the newly formed task force.

The condition was first observed in the 1960s among undernourished populations across India, Pakistan, and parts of sub-Saharan Africa. Originally called J type diabetes, as it was first detected in Jamaica, it was briefly included in the World Health Organisation’s classification in 1985. However, it was removed in 1998 due to lack of solid physiological evidence and was long considered a mismanaged form of existing types of diabetes.

In 2022, renewed attention came through a study conducted by Dr Thomas and Dr Riddhi Dasgupta of CMC, along with Prof Meredith Hawkins of Albert Einstein College of Medicine, New York. Their research demonstrated that Type 5 diabetes is indeed physiologically different from both Type 1 and Type 2. 'Those with Type 5 are insulin deficient, but not insulin resistant. This is a key difference from Type 2 diabetes, where the body resists insulin’s action despite producing it,' Dr Thomas said.

Patients diagnosed with this condition usually have an extremely low Body Mass Index (BMI), often less than 18.5kg/m2. While past studies have shown that babies born with low birth weight who are later overfed may develop Type 2 diabetes, researchers found that those who remain undernourished after birth may instead develop Type 5 diabetes.

Another major distinction is that patients with Type 5 do not have the antibodies commonly seen in Type 1 diabetes. Moreover, nearly half of the affected individuals can be managed with oral medication alone. 'Also, about 50% of them could be managed with tablets, not insulin. This is important as Type 5 is mostly seen in areas of low resources,' Dr Thomas added. In India, for example, cases are more commonly seen in regions with lower gross domestic product (GDP).

The study findings were published in the journal Diabetes Care in 2022. Following this, Scientific American in 2023 published a detailed review that helped bring more international focus to this long-overlooked condition.

Dr Thomas also clarified that Type 5 should not be confused with MODY-5 (Maturity Onset Diabetes of the Young or HNF1-beta mutations), a rare genetic form of diabetes. 'There are about 25 to 30 million cases of Type 5 diabetes worldwide, perhaps more,' he added.