C-Peptide Can Help Diagnose Fulminant Type 1 Diabetes Mellitus
News Author: Laurie Barclay, MD
CME Author: Charles Vega, MD, FAAFP
Aug. 13, 2004 — C-peptide can facilitate the diagnosis of fulminant type 1 diabetes mellitus (DM), according to the results of a study published in the August issue of Diabetes Care.
“The key issue for the diagnosis in this new subtype of type 1 diabetes is absence of autoantibodies against islet cells,” write Shoichiro Tanaka, MD, from the University of Yamanashi in Japan, and colleagues. “However, the measurement of pancreatic autoantibodies including GADAb, ICA, IA-2Ab, and IAA is in the process of being standardized, and these autoantibodies can be measured in a limited number of laboratories.”
Of 125 consecutively recruited patients with type 1 DM, 25 patients had fulminant type 1 DM and 100 had acute-onset type 1 DM. The investigators measured basal and longitudinal changes of serum C-peptide levels during a 75-g oral glucose tolerance test (OGTT) in these patients, and they determined discriminating criteria of fulminant type 1 DM using receiver-operating characteristic curve analysis and multiple logistic regression analysis.
At onset and one and two years after onset, the integrated values of serum C-peptide response during OGTT (ΣC-peptide) in fulminant type 1 DM were considerably lower than those in acute-onset type 1 DM. C-peptide response to OGTT did not improve in any of the patients with fulminant type 1 DM. Compared with those in acute-onset type 1 DM, fasting C-peptide values at onset in fulminant type 1 DM were significantly lower.
To discriminate fulminant type 1 DM from acute-onset type 1 DM with high sensitivity and specificity, the investigators chose diagnostic criteria of serum C-peptide and hemoglobin A1c (HbA1c) levels at onset in which the levels of fasting C-peptide is 0.033 nmol/L or less and HbA1c is 8.0% or less, or a criterion in which the level of the ΣC-peptide is 0.540 nmol/L or less, and HbA1c is 8.0% or less.
The authors acknowledge that criteria based only on serum C-peptide could yield a fair number of false positives in acute-onset type 1 DM.
“Fulminant type 1 diabetes has extremely low ß–cell function at onset that rarely recovers after onset,” the authors write. “Patients with fulminant type 1 diabetes have higher risks of developing diabetes complications than patients with acute-onset type 1 diabetes. Therefore, fulminant type 1 diabetic patients might have a need for accurate diagnosis followed by intensive insulin therapy to attain good and stable glycemic control.”
This study, the fifth of the Yamanashi Diabetes Research Group, was partly supported by grants from the Ministry of Education, Science, Sports, and Culture in Japan and the Japan Diabetes Foundation.
Diabetes Care. 2004;27:1936-1941