Type 5 diabetes recognised as distinct form of disease: why is this significant?

What is Type 5 diabetes?

Type 5 diabetes is a form of diabetes affecting lean and malnourished teenagers and young adults in low- and middle-income countries.

Dr Nihal Thomas, professor of endocrinology at Christian Medical College, Vellore, is among the members of the Type 5 Diabetes Working Group. He told The Indian Express that the disease causes pancreatic beta cells to function abnormally, leading to insufficient production of insulin.

This is unlike Type 2 diabetes, the most prevalent form of the disease, where the main problem is insulin resistance — while the pancreas continues to produce insulin, the body does not respond properly to the hormone.

The term ‘Type 5’ diabetes was introduced and endorsed by Prof Peter Schwarz, president of the IDF, in January this year. On April 7, it was officially recognised at the 75th World Congress for Diabetes in Bangkok.

However, this is not a new disease. It was first reported in Jamaica as early as 1955 under the moniker J-type diabetes. In 1985, the World Health Organization (WHO) classified the condition as “malnutrition-related diabetes mellitus”. But this classification was done away with in 1999 for the want of evidence of a causal link to malnutrition, which is among the definitive features of what is now known as Type 5 diabetes.

It was subsequently reported in many countries, such as India, Sri Lanka, Bangladesh, Uganda, Ethiopia, Rwanda, and Korea, mostly in the Global South. It currently affects an estimated 25 million people globally.

Its official recognition comes on the back of recent research, which has brought renewed attention to the impact of malnutrition on pancreatic development and insulin function, particularly in individuals with poor nutrition in childhood and early adulthood.

What are markers of Type 5 diabetes?

According to Dr Thomas, this unique form of diabetes, observed in Asian Indians, has no evidence of autoimmune or genetic causes.

“Affected individuals have a significantly lower body-mass index (BMI) — of less than 18.5 kg/m2 — than those reported in previous Indian studies. Insulin secretion is severely reduced, much lower than typical Type 2 diabetes and just above levels seen in Type 1 Diabetes,” he said.

“Body scans also reveal a substantially lower percentage of body fat compared to Type 2 diabetes cases. Additionally, dietary intake of proteins, fibre and essential micronutrients is significantly low,” Dr Thomas added.

So, what causes Type 5 diabetes?

Malnutrition. And it all begins in the womb.

Dr C S Yajnik, director, Diabetes Unit, KEM Hospital Pune, and a key member of the Type 5 Diabetes Working Group, explained how malnutrition begins in the mother’s womb.

“If a baby does not get the right amount of nutrition while growing in the womb, it can increase the risk of diabetes later in life. For a long time, many Indians were undernourished due to hard labour, colonisation, and famines. But in the past 50 years, with rapid urban growth and development, overeating has also become a problem. When a baby is under or over nourished before birth and then gains too much weight later, it can lead to Type 2 diabetes. But if the baby stays undernourished both before and after birth, it can lead to this malnutrition-related diabetes, or as now christened, Type 5 diabetes,” he said.

How can Type 5 diabetes be treated?

Given it has only now been officially recognised, specific diagnostic criteria and therapeutic guidelines are yet to be finalised. This is what the aforementioned Working Group will be doing over the next two years, by looking at diverse populations, especially in low-income, low-resource settings.

According to Dr Thomas, a high protein diet is important. Depending on the person’s low BMI and physical activity levels, an adequate amount of carbs and fats are also needed to ensure weight gain.

“Anti-diabetic medicine or insulin is considered based on the level of glucose and the therapeutic response on a case-by-case basis,” he said.