G. Bruno et al., Clinical, immunological, and genetic heterogeneity of diabetes in an Italian population-based cohort of lean newly diagnosed patients aged 30-54 years, DIABET CARE, 22(1), 1999, pp. 50-55
OBJECTIVE - In lean diabetic patients, the presentation of the disease does
not allow one to easily distinguish between type 1 and type 2. Aims of thi
s study were to describe clinical, immunological, and genetic features of l
ean newly diagnosed diabetic patients.
RESEARCH DESIGN AND METHODS - A population-based cohort of 130 lean (BMI <2
5 kg/m(2)) newly diagnosed patients, aged 30-54 years, was identified among
residents of the province of Turin. Islet cell antibodies (ICAs), anti-CAD
, fasting and glucagon-stimulated C-peptide values, and HLA DQA1-DQB1 susce
ptibility genotypes were assessed within 2 months of the diagnosis.
RESULTS - A total of 45 (34.6%) and 29 (22.3%) patients were, respectively,
ICA(+) and anti-GAD(+), with 15 (11.5%) having both antibodies. In 59 pati
ents, ICAs and/or anti-CAD antibodies were detected, giving a high prevalen
ce of autoimmunity (45.4%, 95% CI 36.8-54.0); relative to patients without
markers (n = 71), they were younger (40.8 +/- 7.5 vs. 45.0 +/- 6.5 years, P
< 0.001) and showed lower values of fasting C-peptide (0.56 +/- 0.33 vs. 0
.79 +/- 0.41 nmol/l, P < 0.001) and stimulated C-peptide (1.03 +/- 0.56 vs.
1.42 +/- 0.69 nmol/l, P < 0.001). The lowest stimulated C-peptide values w
ere found in patients with both ICA and anti-CAD antibodies. Frequencies of
adult-onset. type 1 and type 2 diabetes were, respectively 49.2 and 50.8%.
Clinical and genetic features were not useful in the classification of pat
ients.
CONCLUSIONS - Almost 50% of lean young and middle-aged patients were ICA(+)
and/or anti-GAD(+), suggesting a high prevalence of a slowly evolving form
of type 1 diabetes. The evaluation at diagnosis of both beta-cell secretor
y capacity and markers of autoimmunity is recommended to provide a pathogen
etic classification of the disease.