What is Type 5 diabetes? When undernutrition, not sugar, leads to metabolic collapse

Most types of diabetes are linked to overnutrition and sedentary lifestyles. Type 5, however, is found in people with a history of chronic undernutrition, especially those who are lean or underweight (Image: Canva)

Fatigue that lingers for days. Blurry vision that makes it hard to focus. Weight that keeps dropping, despite eating regularly. These symptoms may look like classic signs of diabetes, but in many cases across low- and middle-income countries, standard treatments like insulin don’t work. In fact, they can make things worse.

While diabetes is often linked with obesity and high sugar intake, another form of the disease is driven by the opposite: long-term undernutrition. It’s now officially recognised as Type 5 diabetes, a distinct and serious condition that affects malnourished teens and young adults, mostly in countries with limited resources.

According to the International Diabetes Federation (IDF), over 537 million adults worldwide are living with diabetes — a number expected to rise to 643 million by 2030. While type 2 diabetes makes up the majority of cases, especially in wealthier nations, experts have now identified a separate category: malnutrition-related diabetes, newly classified as Type 5 diabetes.

Because the disease isn’t caused by insulin resistance, insulin injections don’t always work, and can cause hypoglycemia (dangerously low blood sugar) (Image: Canva)

Also read | Prediabetes symptoms, cure: Regular exercise, healthy diet and metformin help control blood sugar level

The global research shows that young, thin people, especially in parts of Asia and Africa, are being diagnosed with a form of diabetes that doesn’t respond like type 1 or type 2 diabetes. Despite being underweight, their bodies struggle not with insulin resistance, but with a serious lack of insulin production. When treated with insulin, their blood sugar may crash dangerously low.

Here’s what you need to know about Type 5 diabetes, and why it’s different:

• Malnourished, not overweight: Most types of diabetes are linked to overnutrition and sedentary lifestyles. Type 5, however, is found in people with a history of chronic undernutrition, especially those who are lean or underweight. These people often lack muscle and fat reserves and may also suffer from micronutrient deficiencies.

• Observed in developing countries: Type 5 diabetes has been reported mostly in South Asia, Sub-Saharan Africa, and parts of Latin America, where poverty, famine, and food insecurity are still major public health issues. It's especially common in rural or low-resource settings where access to healthcare is limited.

• Insulin treatment may not be effective: Because the disease isn’t caused by insulin resistance, insulin injections don’t always work, and can cause hypoglycemia (dangerously low blood sugar). This makes treatment especially risky and calls for specialised protocols that suit these patients.

• Poor insulin production: Recent studies show that the pancreas in people with Type 5 diabetes is damaged or underdeveloped, likely due to long-term malnutrition in early life. This leads to low or inconsistent insulin secretion, making blood sugar management difficult.

• Misclassified for decades: Though the World Health Organization recognised this form in 1985, it was removed from classifications in 1999 due to limited data. This left many patients without a name for their condition, further delaying research, awareness, and treatment strategies.

• Official recognition: The IDF’s classification of Type 5 diabetes as a distinct disease allows researchers to seek funding, develop treatments, and create diagnostic guidelines. It also brings hope for training healthcare providers in rural areas to better recognise and manage it.

• Early death: Without appropriate care, many patients with Type 5 diabetes do not survive more than a year after diagnosis. Recognition and proper treatment could drastically reduce this tragic outcome.

Type 5 patients may have blood sugar levels that fluctuate unpredictably, and traditional risk factors like high BMI or family history often don’t apply. It’s this atypical presentation that makes diagnosis particularly challenging.

Disclaimer: This article, including health and fitness advice, only provides generic information. Don’t treat it as a substitute for qualified medical opinion. Always consult a specialist for specific health diagnosis.