# An “unclassified diabetes” after a long duration of disease in a young subject: a case report

## TL;DR

This case report describes a young patient with diabetes that was initially classified as type 1 but later showed features that challenge this diagnosis.

## Contribution

The case highlights the challenges in diagnosing diabetes subtypes and suggests unclassified diabetes may not always be temporary.

## Key findings

- The patient had high insulin requirements and negative autoantibodies, but also residual insulin secretion.
- Diabetes remission occurred before sudden death from hepatocellular failure, complicating the initial diagnosis.
- The case shows that unclassified diabetes may persist and not resolve with further investigation.

## Abstract

Unclassified diabetes describes diabetes that does not fit into other categories. This category is used temporarily when there is no clear diagnostic category, especially close to the time of diagnosis. This implies that paraclinical investigations or the natural evolution of the disease will allow a definitive classification. We present the case of diabetes initially classified as type 1 in an adolescent. For ten years, the patient had high insulin requirements with negative autoantibodies, significant residual insulin secretion, and for the last 3 months of life, remission of diabetes in the context of a wound of the thigh, before a sudden death from hepatocellular failure, pushing to reconsider the initial diagnosis. This clinical case highlights difficulties in obtaining precision in the etiological diagnosis of diabetes in some patients based either on clinical manifestation, biological assessment, or evolution. It also shows that unclassified diabetes subtypes may not be transient.