Classification of diabetes in young Asians based on islet autoimmunity and beta-cell function. [Abstract]

Backgrounds and aims: The Asian Young Diabetes (ASDIAB) project is a five-year prospective study on the clinical and immunological characterisation of diabetes in newly diagnosed young Asians. This paper aims at evaluating the aetiological classification of diabetes in these patients based on presence/absence of islet autoantibodies and beta cell function at disease presentation and one year.
Materials and methods: A total of 919 patients (from Beijing, Shanghai, Hong Kong, India, Malaysia and Singapore) with age at diagnosis 12-40 years and diabetes duration <12 months were recruited between 1997 and 1999. Complete information on autoantibodies to glutamic acid decarboxylase (GAD) and IA-2 and fasting C-peptide at baseline and 1 year were available in 633 patients. Antibody positivity (Ab+) was defined by presence of GADab and/or IA-2 abo Poor beta-cell function was defined with fasting C-peptide <0.3nM at one year. TlDM was identified in patients Ab+ at diagnosis (irregardless of p cell function status) and in those Ab- at diagnosis and I-year, but demonstrated poor beta-cell function at I-year. Patients who were Ab- at diagnosis and I-year but had good beta cell function (fasting C-peptide >=0.3nM) at I-year were classified as having type 2 diabetes (T2DM).
Results: 139 patients (22%) were classified as having T1DM. Of these, 90 were Ab+ and 49 were Ab- and had poor beta cell function. The remainder 494 patients (78%) were classified as having T2DM. The ethnic distribution of T1DM patients (73% Chinese, 16% Indians and 11 % Malays) was similar to the T2DM. Compared to T2DM, T1DM patients were significantly younger at diagnosis (mean age 28.0 vs 32.9 yrs), leaner (mean BMI 21.5 kg/m' vs 25.9 kg/m' at diagnosis, 22.0 kg/m2 vs 26.1 kg/m2 at 1 year), and had significantly higher HbA1 , (11.8% vs 9.7% at diagnosis; 8.9% vs 8.0% at 1 year) . Median fasting C-peptides were significantly lower in T1DM than T2DM patients (0.2 vs 0.7 nM at diagnosis; 0.2 vs 0.8 nM at 1 year). T2DM were more insulin resistant than T1DM patients as assessed by HOMA index (median 5.8 vs 4.4 at diagnosis, 4.9 vs 3.4 at 1 year).
Conclusions: In Asians with young onset diabetes, assessment at diagnosis and one year for islet autoantibodies (GADab and lor IA-2Aab), together with estimation of p-cell function with fasting serum C-peptide levels, were useful for classifying patients as having T1DM and T2DM .
Grant from Novo Nordisk Asia Pacific, Singapore
40th EASD Annual Meeting of the European Association for the Study of Diabetes : Munich, Germany, 5-9 September 2004