When Diabetes Diagnosis Changes: A Case of Flatbush Diabetes and Infection

A 36-year-old man from Eritrea developed sudden onset symptoms including frequent urination, excessive thirst, fatigue, and significant weight loss. Blood tests showed very high blood sugar (19.2 mmol/L) and an HbA1c of 97 mmol/mol, indicating sustained high glucose levels. Initially, doctors diagnosed Type 1 diabetes and started insulin treatment. However, the clinical picture didn't fit neatly into the typical Type 1 diabetes story.

While investigating the patient's overall health, imaging and blood work revealed something unexpected: signs of liver disease, an enlarged spleen, and positive tests for schistosomiasis—a parasitic infection common in parts of Africa and the Middle East. Further testing, including liver biopsy and PCR analysis, confirmed the schistosomiasis diagnosis. This finding shifted the clinical picture entirely.

Flatbush diabetes is a rare form of diabetes that presents with symptoms resembling Type 1 diabetes—including high blood sugar and initial insulin need—but lacks the autoimmune markers typical of Type 1. In this case, when doctors checked for autoantibodies (proteins that signal autoimmune attack on insulin-producing cells), they were negative. This absence was a crucial clue that something other than autoimmune Type 1 diabetes was occurring.

The patient's schistosomiasis infection appeared to be the trigger for the high blood sugar and diabetes-like symptoms, rather than an autoimmune attack on the pancreas.

After three months, with treatment for the underlying infection underway, the patient's blood sugar normalized without insulin. C-peptide levels—a marker of the body's own insulin production—increased, and autoantibodies remained negative. The diagnosis was revised from Type 1 diabetes to Flatbush diabetes secondary to schistosomiasis.

This case underscores an important principle: when high blood sugar appears suddenly alongside other systemic signs of illness, investigating the whole clinical picture—including infections and other non-autoimmune causes—can lead to the correct diagnosis and more effective treatment.

Source: Ugeskrift for laeger. 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.