BMJ

Sixty seconds on type 5 diabetes

October 10, 2025

In April this year the International Diabetes Federation (IDF) agreed to recognize type 5 diabetes, saying that evidence supported a distinct new classification. In a comment published in the Lancet Global Health this week, the IDF urged global health bodies, including the World Health Organization, to follow suit.¹

Type 5 is a distinct form of diabetes linked to chronic undernutrition and health disparities. Some 25 million people (around 4% of the 589 million people with diabetes globally) are estimated to be affected, most of whom live in South East Asia and Sub-Saharan Africa. It was first described in patients in Jamaica in the 1950s; they had typical symptoms of diabetes but were unusually thin. The name “type J” didn’t take off, however, and while WHO recognized malnutrition related diabetes as a distinct condition in 1985 it removed the definition in 1995, saying there was insufficient evidence from follow-up studies.

How would we recognize the type?

People with type 5 diabetes, similar to those with type 1, cannot produce enough insulin. But, unlike type 1, type 5 is not caused by an autoimmune disorder and rarely causes ketoacidosis—a dangerous buildup of acid in the blood when the body runs out of insulin. Unlike people with type 2 diabetes, however, those with type 5 can use the insulin they make, they just don’t create enough. Researchers believe that what distinguishes type 5 is the chronic undernutrition that causes it. Being malnourished from the womb until adulthood likely changes how the pancreas develops.

Lean but mean?

Without proper care there is an increased risk of nerve damage, kidney disease, and vision problems. Life expectancy after diagnosis is often just over a year.² The IDF says treatment is worsened by frequent misdiagnosis. Because it is caused by malnutrition, telling people with the condition to lose weight is dangerous. So too can be injecting them with insulin, which may cause fatal blood sugar levels.

No resistance here?

Not quite. Some are pushing back, arguing there aren’t enough data to distinguish type 5 from type 2 diabetes. “Formal classification risks codifying what may be a spectrum of poorly characterized type 2 diabetes rather than a discrete entity,” Anoop Misra, an endocrinologist at the Centre of Nutrition and Metabolic Research in New Delhi told NPR Goats and Soda.³

The fifth amendment?

The IDF says it will continue to push for recognition of type 5 diabetes so it can be better studied and treated. It has set up a working group to create clear diagnostic criteria and educate healthcare providers. “By acknowledging the distinct pathophysiology of type 5 diabetes and the social determinants driving its emergence, we are tackling a long neglected condition affecting millions of people in under-resourced regions,” IDF president Peter Schwarz told The BMJ.

References:

1. Wadivkar P, Jebasingh F, Thomas N, et al., Vellore Declaration Signatories. Classifying a distinct form of diabetes in lean individuals with a history of undernutrition: an international consensus statement. Lancet Glob Health 2025;13:e1771-6. doi:10.1016/S2214-109X(25)00263-3 pmid:40975084CrossRefPubMedGoogle Scholar

2. The long overdue classification of type 5 diabetes. Diabetes Voice. https://diabetesvoice.org/en/caring-for-diabetes/the-long-overdue-classification-of-type-5-diabetes

3. Neglected form of diabetes with unusual symptoms finally gets its own name. NPR Goats & Soda. www.npr.org/sections/goats-and-soda/2025/09/29/g-s1-90669/neglected-form-of-diabetes-with-unusual-symptoms-finally-gets-its-own-name

Source:

Taylor L. Sixty seconds on ... type 5 diabetes. BMJ 2025;391:r2092 doi:10.1136/bmj.r2092