# A Case of Fulminant Type 1 Diabetes With Residual Insulin Secretion

## TL;DR

An elderly woman with fulminant type 1 diabetes showed unexpected recovery of insulin production over time.

## Contribution

Demonstrates residual and recovering insulin secretion in a rare case of fulminant type 1 diabetes.

## Key findings

- Initial C-peptide levels were low, suggesting little insulin production.
- After two months, C-peptide levels increased significantly during a glucagon stimulation test.
- Daily urinary C-peptide levels indicated some ongoing insulin secretion.

## Abstract

A 67-year-old woman presented with fever and a cold a week later, with symptoms of hyperglycemia. After 10 days, her non-fasting blood glucose level was 586 mg/dL, and glycosylated hemoglobin (HbA1c) was 7.2%. She then developed diabetic ketosis and was treated with insulin. Her fasting C-peptide immunoreactivity (CPR) became 0.4 ng/mL. However, her insulin requirement was subsequently reduced. After two months, her CPR was 1.07 ng/mL at zero minutes and 2.04 ng/mL at six minutes in a glucagon stimulation test. Daily urinary CPR was 62 mg. Even though fulminant type 1 diabetes was indicated from the clinical course, insulin secretory ability improved.