Type 5 Diabetes Mellitus: Global Recognition of a Previously Overlooked Subtype

A once-overlooked form of diabetes, previously known as malnutrition-related diabetes, has now received official recognition from the International Diabetes Federation (IDF) as Type 5 Diabetes Mellitus (T5DM). This pivotal decision was finalized on April 8, 2025, through a formal vote at the World Diabetes Congress in Bangkok, Thailand.[1] T5DM is estimated to affect 20–25 million individuals globally, particularly in low- and middle-income countries across Asia and Africa. The IDF’s recognition represents a significant advancement in our understanding of diabetes pathophysiology, particularly among lean adolescents and young adults exposed to chronic undernutrition. This condition falls under the classification of severe insulin-deficient diabetes. Unlike Type 1 diabetes, which arises from autoimmune destruction of pancreatic beta cells, or Type 2 diabetes, characterized by insulin resistance, Type 5 diabetes stems from impaired pancreatic development–a consequence of sustained nutritional deprivation during critical growth periods, such as childhood or adolescence. As such, it is clinically distinct from both major types. Historically, this subtype was first described in Jamaica in 1955 and later acknowledged by the World Health Organization in 1985.[2] However, due to limited mechanistic evidence, it was removed from formal classification in 1999.[3] Interest in the condition reemerged in the early 2000s through the efforts of Dr. Meredith Hawkins, Professor of Medicine at Albert Einstein College of Medicine. Hawkins, now the chair of the IDF Type 5 Diabetes Working Group, founded the Global Diabetes Institute in 2010, which has become a hub for research into underrecognized forms of diabetes. In a 2022 metabolic study led by Hawkins et al., 73 lean Asian Indian men were assessed using advanced testing protocols.[4] Among them, 20 participants met the criteria for T5DM, exhibiting profound insulin secretory failure, low hepatic and visceral fat levels, enhanced glucose uptake, and reduced endogenous glucose production. These characteristics contradicted earlier assumptions that malnutrition-related diabetes was driven by insulin resistance. Instead, the data highlighted a distinct metabolic phenotype marked by severe insulin deficiency.[4] While the American Diabetes Association currently categorizes diabetes into four broad groups–Type 1, Type 2, gestational diabetes, and diabetes from specific causes including monogenic and secondary forms–malnutrition-related diabetes has remained ambiguously classified.[5] The IDF’s official designation of Type 5 diabetes thus closes a long-standing gap in global diabetes taxonomy. Dr. Hawkins underscored the significance of this development in an interview with Medscape Medical News: “Recognition of this condition as ‘Type 5 diabetes’ by the IDF is a critical milestone. It brings long-overdue visibility to a disease that disproportionately affects vulnerable populations and has been left out of Western-focused medical texts and guidelines.”[6] She also cautioned against the potentially fatal consequences of misdiagnosing T5DM as Type 1 diabetes, as standard high-dose insulin regimens may not be safe for these individuals. Instead, low-dose insulin combined with oral hypoglycemics appears more appropriate. Further, nutritional strategies–such as protein-rich, low-carbohydrate diets, and micronutrient supplementation–may offer therapeutic benefits, although additional research is needed to establish effective clinical protocols. Following its recognition, the IDF has established a dedicated working group to create formal diagnostic criteria and treatment guidelines. These are expected to be published within the next 2 years.[1] The inclusion of T5DM in global diabetes classification systems represents not only a scientific breakthrough but also a vital step toward health equity. By addressing the needs of populations most impacted by poverty and chronic undernutrition, this development opens the door to more accurate diagnosis, effective management, and targeted research efforts worldwide. NEXT STEPS The IDF has convened a working group to establish diagnostic criteria and guidelines by 2027. This recognition underscores the need for: Population-specific screening in malnutrition-prone regions Clinical trials to optimize treatment Policy shifts to address underlying socioeconomic drivers.