Type 5 Diabetes: A Distinct Condition Linked to Early-Life Undernutrition

A distinct form of diabetes affecting lean, young people with a history of severe undernutrition was first described in the 1950s. Doctors noticed something paradoxical: patients had severe high blood sugar levels and low body weight, but did not develop ketosis—a dangerous buildup of acids in the blood that typically occurs in type 1 diabetes.

For decades, this condition was called malnutrition-related diabetes mellitus (MRDM). The World Health Organization recognized it as a separate category in 1985, but removed it from official classification in 1999 due to lack of clear evidence about how it developed. Over the next 25 years, research in low- and middle-income countries revealed distinct metabolic features that set this diabetes apart from both type 1 and type 2. In 2025, the International Diabetes Federation formally endorsed this as type 5 diabetes mellitus (T5DM).

Type 5 diabetes is estimated to affect approximately 20–25 million people worldwide. It predominantly affects young individuals with low body mass index who live in low- and middle-income countries. The condition is closely linked to a history of early-life undernutrition.

Type 5 diabetes has a unique metabolic profile that distinguishes it from both type 1 and type 2 diabetes. People with type 5 diabetes have impaired insulin secretion—meaning their pancreas does not produce enough insulin—but their bodies remain sensitive to the insulin they do produce. Importantly, type 5 diabetes does not involve autoimmune markers, which are present in type 1 diabetes.

Another key difference is resistance to ketosis. Even when blood sugar levels are severely elevated, people with type 5 diabetes typically do not develop ketosis, unlike those with type 1 diabetes. This unusual combination of severe high blood sugar without ketosis was one of the first clues that this was a distinct condition.

Recent research suggests that early-life undernutrition plays a central role in the development of type 5 diabetes. Malnutrition during critical periods of growth appears to disrupt the development of the pancreas and the cells that produce insulin, called beta cells. This disruption leads to persistent structural deficits in the pancreas and reduces the functional reserve of beta cells that can be drawn upon in adulthood.

In other words, severe undernutrition during childhood may permanently limit how much insulin a person's pancreas can produce later in life, setting the stage for diabetes to develop.

Correctly identifying type 5 diabetes is important for treatment. When the condition is mistakenly classified as type 1 diabetes, patients may be started on lifelong intensive insulin therapy, which may not be the most appropriate or necessary approach for their specific condition. Type 5 diabetes requires an integrated treatment strategy that addresses both nutrition and medication, tailored to the distinct features of the disease.

Source: Endokrynologia Polska. Evidence type: PubMed indexed literature. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.