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A new classification in a complex disease landscape
The International Diabetes Federation has formally recognised a distinct, malnutrition-related form of diabetes commonly called "Type 5". This decision reflects growing evidence that diabetes is not a single disease but a family of conditions with different causes, trajectories and treatment needs. Understanding these subtypes—ranging from autoimmune forms to genetically driven and injury-related diabetes—is essential for accurate diagnosis, targeted therapy and global health planning.
Diabetes is defined by persistently elevated blood glucose (sugar) due to problems in insulin production, insulin action, or both. Insulin is a hormone produced by the pancreas that allows cells to absorb glucose for energy. However, the mechanisms that lead to high blood sugar vary widely and determine the most appropriate interventions.
Common forms: Type 1, Type 2 and gestational diabetes
Type 1 diabetes is an autoimmune condition in which the body's immune system destroys insulin-producing beta cells in the pancreas. This destruction reduces or eliminates endogenous insulin production and can occur at any age—from infancy to late adulthood. Type 1 is not caused by diet or lifestyle. Genetic predisposition combined with environmental triggers, such as viral infections, are thought to initiate the autoimmune process. Treatment requires lifelong insulin replacement delivered via injections or insulin pumps. Advanced therapies, including donor islet cell transplants and experimental stem-cell-derived beta-cell transplants, have shown promise for some patients but remain limited by immune-suppression requirements and availability.
Type 2 diabetes is the most prevalent form worldwide. It typically involves insulin resistance—where tissues respond poorly to insulin—and, over time, impaired insulin secretion from the pancreas. High body mass index (BMI) and excess adiposity are important risk factors, but genetics, age and ethnicity also play major roles; people of South Asian, African and Caribbean ancestry have elevated risk even at lower body weights. Treatments include lifestyle modification, dozens of glucose-lowering medications (for example, metformin, GLP-1 receptor agonists, SGLT2 inhibitors) and, in some cases, bariatric surgery. Intensive dietary interventions and weight loss have reversed type 2 diabetes for many individuals in clinical trials.
Gestational diabetes emerges during pregnancy, usually between the second and third trimesters, when hormonal changes reduce insulin sensitivity. Risk factors include higher maternal weight, older maternal age and family history. Ethnic background also influences risk. Management focuses on blood glucose monitoring, nutrition and physical activity; some women require medication or insulin during pregnancy. Postpartum follow-up is essential because gestational diabetes increases the mother’s long-term risk of type 2 diabetes and may signal metabolic risk for the child.
Rare and secondary forms: genetic syndromes, pancreatic disease and beyond
Beyond types 1 and 2 there are multiple less common forms of diabetes with distinct causes and treatment implications. Monogenic diabetes includes neonatal diabetes—present in the first months of life—and maturity-onset diabetes of the young (MODY), which often presents in adolescence or early adulthood. These subtypes are caused by single-gene variants that affect beta-cell function, insulin secretion or pancreatic development. Some patients with specific gene variants can be treated with oral medications rather than insulin.
Type 3c diabetes arises from direct damage to the pancreas, such as surgical removal of pancreatic tissue, chronic pancreatitis or pancreatic cancer. This form combines loss of insulin production with defects in digestive enzyme secretion and often requires tailored insulin therapy plus attention to nutritional deficiencies. Cystic fibrosis–related diabetes is common in adults with cystic fibrosis, becoming more prevalent with age as pancreatic function declines.
Other secondary causes include steroid-induced diabetes and hyperglycaemia following certain medications or therapies. Correctly identifying these causes is important: some forms are reversible if the underlying trigger is removed, whereas others require lifelong management.
Type 5: Malnutrition-related diabetes—scientific context and clinical features
Type 5 diabetes, now recognised as a separate category, is linked to early-life undernutrition and impaired pancreatic development. It is more common in low- and middle-income countries and is estimated to affect roughly 20–25 million people worldwide. Clinically, people with type 5 often present with low body weight and a primary deficiency in insulin production rather than immune-mediated beta-cell destruction.
Animal studies show that inadequate maternal or adolescent dietary protein impairs pancreatic growth and reduces the pool of insulin-producing cells. A smaller or underdeveloped pancreas offers fewer beta cells to meet metabolic demands in adulthood, increasing vulnerability to hyperglycaemia. Unlike type 1, the pancreas is not targeted by autoimmunity; unlike typical type 2, insulin resistance may be less prominent. These distinctions have practical implications for treatment: some patients may benefit more from strategies that support beta-cell function and nutritional rehabilitation rather than the standard insulin-sensitising or weight-loss approaches used for type 2.
Recognising type 5 prompts shifts in public health priorities: improving maternal and child nutrition, fortifying diets, and monitoring high-risk populations could reduce the lifetime burden of diabetes in resource-limited settings.
Implications for diagnosis and treatment
Accurate classification requires clinical history, anthropometry (body measurements), laboratory testing (autoantibodies, C-peptide to estimate insulin production) and, when indicated, genetic testing. For type 5, a history of early-life malnutrition and low BMI in adulthood are suggestive. Treatment pathways may include nutritional rehabilitation, careful glycaemic management, and tailored use of insulin or secretagogues depending on residual beta-cell function.
Expert Insight
"Recognising malnutrition‑related diabetes as a specific category is a major step toward equitable diabetes care," says Dr. Elena Rios, a fictional endocrinologist specialising in global metabolic health. "Clinicians working in low-income settings need diagnostic tools and treatment algorithms adapted to patients with low BMI and limited access to advanced therapies. Public health measures—improving maternal nutrition, childhood protein intake and early screening—are key to prevention."
This expert perspective highlights the intersection between clinical endocrinology and global nutrition policy. The new classification can guide research funding, diagnostic resource allocation and tailored treatment trials in regions where undernutrition persists.
Conclusion
Diabetes encompasses a spectrum of disorders with distinct causes, clinical presentations and treatment needs. The formal recognition of Type 5—malnutrition-related diabetes—underscores the role of early-life nutrition and pancreatic development in lifelong metabolic health. For clinicians and health systems, the priority is accurate diagnosis, individualised treatment and prevention through improved maternal and child nutrition. For researchers, this reclassification opens new avenues to study pancreatic development, nutritional interventions, and cost-effective therapies targeted to undernourished populations. As the scientific community refines diabetes taxonomy, patients worldwide stand to benefit from more precise, context-sensitive care.
(dashapetrenkophotos/Canva)
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