Clinical heterogeneity of type 1 diabetes mellitus at onset

Objective To investigate the clinical heterogeneity of type 1 diabetes mellitus (T1DM) at onset. Method A total of 205 newly diagnosed T1DM patients discharged from the hospital between January 1999 and December 2009 were retrospectively reviewed. Clinical characteristics and laboratory data at onset were compared among fulminant type 1 diabetes (FT1DM) and those with duration of symptoms before diagnosis shorter (acute-onset) or longer (slow-onset) than 3 months. Antibodies to glutamic acid decarboxylase (GADA) were determined by enzyme-linked immunosorbent assay (ELISA), while islet cell antibodies (ICA) , insulin autoantibody(IAA) and serum C-peptide were detected using radioimmunoassay (RIA). Statistical analyses were performed using One-way ANOVA and two independent samples t-test for measurement data, multivariate Chi-square and Fisher's exact probability test were used for enumeration data. Results The proportions of FT1DM, acute-onset and slow-onset T1DM were 8.8%, 66.8%, 24.4% respectively. The onset of FT1DM was so abrupt that the concentration of plasma glucose was prominently elevated ((31±12) vs (25±10), (24±8) mmol/L, F=4.462, P<0.05), whereas HbA1c was disproportionately near normal ((6.8±1.1)% vs (12.3±2.4)%, (13.9± 2.7)%, F= 54.661, P<0.05). Ketoacidosis was almost inevitable at diagnosis (93.8% vs 45.3%, 8.0%, F= 44.943, P=0.000) and the accompanied metabolic derangement. Hyponatremia, hyperkalemia, acidosis, association with liver and kidney dysfunction was more severe in FT1DM group. Association with pregnancy was more frequent as compared to the other 2 groups (22.2% vs 0, 0, χ2=20.982, P=0.000). Patients with slow-onset type were relatively older and had greater BMI but lost more weight at diagnosis. The post-load C-peptides were relatively higher( (0.40±0.36) vs (0.10±0.13), (0.34±0.26) nmol/L, F=8.752, P<0.05) in this group. Children and adolescents constituted a greater proportion in the acute-onset T1DM group, and the clinical characteristics were similar to the adult-onset counterpart. Conclusions Clinical heterogeneity in the 3 groups is apparent, which might indicate different mechanisms that trigger the development of T1DM leading to the phenotypic discrepancy. Key words: Diabetes mellitus, type 1; Fulminant; Heterogeneity