Distinct Diagnostic Criteria of Fulminant Type 1 Diabetes Based on Serum C-Peptide Response and HbA1c Levels at Onset

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Abstract
OBJECTIVE—Diagnostic criteria in fulminant type 1 diabetes, a novel subtype of type 1 diabetes, remain unclear. RESEARCH DESIGN AND METHODS—We analyzed basal and longitudinal changes of serum C-peptide levels during a 75-g oral glucose tolerance test (OGTT) in 125 consecutively recruited patients with type 1 diabetes including fulminant type 1 diabetes (n = 25) and acute-onset type 1 diabetes (n = 100). Discriminating criteria of fulminant type 1 diabetes were examined using receiver-operating characteristic curve analysis and multiple logistic regression analysis. RESULTS—The integrated values of serum C-peptide response during OGTT (ΣC-peptide) in fulminant type 1 diabetes at onset, 1 year, and 2 years after onset were markedly lower than those in acute-onset type 1 diabetes. None of the patients with fulminant type 1 diabetes had improvement of C-peptide response to OGTT. Fasting C-peptide values at onset in fulminant type 1 diabetes were significantly lower than those in acute-onset type 1 diabetes. We established diagnostic criteria of serum C-peptide and HbA1c levels at onset that discriminate fulminant type 1 diabetes from acute-onset type 1 diabetes with high sensitivity and specificity: a criterion in which the levels of both the fasting C-peptide is ≤0.033 nmol/l and HbA1c is ≤8.0% or a criterion in which the levels of both the ΣC-peptide is ≤0.540 nmol/l and HbA1c is ≤8.0%. CONCLUSIONS—Fulminant type 1 diabetes has extremely low β-cell function at onset that rarely recovers after onset. Sensitive and specific diagnostic criteria were established for detection of fulminant type 1 diabetes based on serum C-peptide and HbA1c levels at onset.