[Use of ABC typing to redefine subtypes of acute-onset type 1 diabetes mellitus: study of 308 patients].

Objective: To investigate the feasibility of ABC typing to redefine the subtypes of acute-onset type 1 diabetes mellitus (DM).

Methods: Radioligand assay was used to detect glutamic acid decarboxylase-antibody (GAD-Ab) and tyrosine phosphatase autoantibody (IA-2A) in 308 patients with acute-onset type 1 DM. The patients were thus divided into 2 groups: pancreatic islet auto-antibody (demonstrated as A) positive group--positive in GAD-Ab or IA-2A--and pancreatic islet auto-antibody negative group. The clinical features and frequencies of HLA-DQ genotypes of these groups were compared. Within 24 hours after the correction of diabetic ketosis or diabetic ketoacidosis and after fasting for at least 8 h fasting and postprandial venous blood samples were collected to detect the fasting C peptide (FCP, demonstrated as B) reflecting the beta cell function, and postprandial C peptide (PCP). The patients were followed up for 2 years to know the insulin dosage (< 20 U/d or > or = 20 U/d). Receiver operating characteristic curve (ROC) was drawn to judge the values of fasting C peptide, body mass index (BMI, demonstrated as C) reflecting the central obesity, and HLA-DQ genotype in further typing among the A + and A - patients and the optimal cutoff points thereof.

Results: Compared with the A - group, the metabolic disorders at the onset were more severe, the insulin dosage at the 2-year follow-up was higher, and the percentage of susceptible HLA-DQ genotype was higher in the A + group (P < 0.05 or < 0.01). The level of FCP (B) could be used to further subtyping in both A + and A - groups, with the optimal cutoff point of 150 pmol/L in the A + group and with the optimal cutoff point of 250 pmol/L in the A - group. BMI could be used for further classification in only A - group with the optimal cutoff point of 24 kg/m2. HLA-DQ genotypes were of little value in further classification both in A + and A - groups.

Conclusion: ABC typing may be used as a new way to redefine the subtypes in acute-onset type 1 DM for prognosis.