Type 5 diabetes explained: The overlooked diabetes affecting young, thin people

What Is type 5 diabetes, and why the world is only now paying attention

For decades, diabetes has largely been understood through two dominant lenses: type 1, an autoimmune condition, and type 2, commonly linked to obesity and lifestyle. But a newly recognized condition, type 5 diabetes, is challenging those assumptions and forcing the global medical community to rethink what diabetes really looks like.

After nearly 70 years of being overlooked, type 5 diabetes has now been officially recognized by the International Diabetes Federation (IDF), bringing long-overdue attention to a form of the disease that primarily affects young, slim, and often undernourished people, particularly in low- and middle-income countries.

A condition first seen in the 1950s, and then forgotten

Type 5 diabetes was first identified in 1955 in Jamaica by Dr. Philip Hugh-Jones, who observed patients with diabetes symptoms that did not fit type 1 or type 2. Initially termed “Type J”, the condition later appeared in global health literature as malnutrition-related diabetes mellitus and was briefly classified by the World Health Organization in the 1980s.

However, due to limited evidence and research, the classification was dropped in 1999, leaving millions of patients misdiagnosed—or not diagnosed at all.

What exactly is type 5 diabetes?

Diabetes develops when the body cannot produce enough insulin or cannot use it effectively. What makes type 5 diabetes distinct is how insulin deficiency occurs.

Experts now believe people with type 5 diabetes:

• Can produce insulin
• Are not insulin resistant
• But have an underdeveloped or damaged pancreas, often due to chronic malnutrition during childhood or adolescence

As a result, insulin production is insufficient, but not absent—placing type 5 diabetes somewhere between type 1 and type 2, yet clearly separate from both.

According to current estimates, up to 25 million people worldwide may be living with type 5 diabetes, most of them undiagnosed.

Who is most at risk?

Type 5 diabetes is most commonly seen in:

• Slim teenagers and young adults
• People with a body mass index (BMI) below 18.5
• Populations in Asia, Africa, and other low-resource regions
• Individuals with a history of childhood malnutrition

Experts also warn that refugees, migrants, and people with eating disorders may be at higher risk—even in high-income countries.

Symptoms: why it’s so often misdiagnosed

The symptoms of type 5 diabetes closely resemble those of Type 1 diabetes, including:

• Excessive thirst
• Frequent urination
• Fatigue
• Blurred vision
• Headaches
• Slow-healing cuts or sores

These symptoms also overlap with signs of malnutrition, such as weight loss and persistent hunger, making diagnosis even more challenging.

Because patients are young and thin, many are incorrectly diagnosed with type 1 diabetes and placed on full-dose insulin therapy—which can be ineffective or even dangerous.

Why insulin alone doesn’t work

Unlike type 1 diabetes, where insulin is essential for survival, patients with type 5 diabetes often respond poorly to insulin therapy. In some cases, insulin can cause dangerously low blood sugar levels.

Instead, emerging evidence suggests treatment should focus on:

• Nutritional rehabilitation
• High-protein diets
• Adequate intake of zinc, magnesium, and B vitamins
• Careful, low-dose insulin use only when necessary

This nutritional-first approach reflects the root cause of the disease: impaired pancreatic development due to malnutrition, not autoimmune destruction.

The science that reignited global attention

Interest in type 5 diabetes surged after the Young-Onset Diabetes in Sub-Saharan Africa (YODA) study, published in The Lancet Diabetes & Endocrinology.

Researchers studied nearly 900 young adults previously diagnosed with type 1 diabetes and found that:

• Two-thirds lacked autoimmune markers typical of type 1
• Many still produced small but measurable amounts of insulin
• Insulin levels were lower than type 2, but not absent

A follow-up call to action in The Lancet Global Health urged international health bodies to formally recognize this distinct diabetes phenotype, warning that misdiagnosis has harmed millions of lives worldwide.

Why this matters globally

Diabetes already affects hundreds of millions of people worldwide. Misclassifying type 5 diabetes:

• Leads to ineffective treatment
• Increases risk of complications
• Shortens life expectancy
• Masks the true global burden of the disease

According to experts, some patients with untreated or mismanaged type 5 diabetes do not survive beyond a year after diagnosis—a stark reminder of the consequences of delayed recognition.

What patients and clinicians should know now

If a young, underweight patient presents with diabetes symptoms, especially with a history of food insecurity, type 5 diabetes should be considered. Proper diagnosis requires:

• Blood glucose testing
• Insulin level assessment
• Autoimmune marker screening
• Nutritional evaluation

As research continues, global recognition of type 5 diabetes marks a crucial shift toward more equitable, accurate, and life-saving diabetes care.

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