Sex- and season-dependent differences in C-peptide levels at diagnosis of immune-mediated type 1 diabetes.
; ; et al
in Diabetologia (2006), 49(6), 1158-62
AIMS/HYPOTHESIS: The incidence of type 1 diabetes varies according to age, sex and season of diagnosis. We investigated whether these and other clinical, biological and anthropometric parameters were ... [more ▼]
AIMS/HYPOTHESIS: The incidence of type 1 diabetes varies according to age, sex and season of diagnosis. We investigated whether these and other clinical, biological and anthropometric parameters were correlated with residual beta cell function in newly diagnosed patients, since it is possible that the nature of external and/or genetic disease accelerators may be (partly) reflected in the inaugural disease presentation. MATERIALS AND METHODS: The correlates of random C-peptide levels sampled shortly after diagnosis (median [interquartile range]: 3 [0-14] days) were studied by multivariate analysis in 1,883 islet-antibody-positive diabetic patients aged <40 years who were diagnosed between 1989 and 2000. RESULTS: Higher C-peptide levels (above percentile 50 of patients) were associated with older age at diagnosis, female sex, diagnosis in the high-incidence season (October to March), less-decreased BMI (expressed as a standard deviation score), lower insulin requirements after stabilisation, lower prevalence of ketonuria and a less-increased glycaemia at diagnosis (all p < 0.001). C-peptide levels were not correlated with calendar year at diagnosis, duration of symptoms prior to diagnosis, HLA-DQ2/DQ8 genotype or islet antibody status. CONCLUSIONS/INTERPRETATION: Sex- and season-dependent differences in residual functional beta cell mass and/or insulin resistance have been identified at diagnosis of type 1 diabetes. They may reflect differences in disease-precipitating external or lifestyle factors and should be further investigated longitudinally in prediabetes to further identify putative aetiological factors, which may provide targets for prevention. [less ▲]Detailed reference viewed: 15 (0 ULg)
Relation between disease phenotype and HLA-DQ genotype in diabetic patients diagnosed in early adulthood
; ; Daubresse, Jean-Claude et al
in Journal of Clinical Endocrinology and Metabolism (2002), 87(6), 2597-2605
We investigated inaugural disease phenotype in relation to the presence or absence of diabetes-associated autoantibodies and human leukocyte antigen (HLA) DQ risk genotypes in adult-onset diabetic ... [more ▼]
We investigated inaugural disease phenotype in relation to the presence or absence of diabetes-associated autoantibodies and human leukocyte antigen (HLA) DQ risk genotypes in adult-onset diabetic patients. Blood samples and questionnaires were obtained from 1584 recent-onset Belgian Caucasian patients (age 15-39 yr at diagnosis of primary diabetes) who were recruited by the Belgian Diabetes Registry over an 11-yr period. At clinical diagnosis, antibody-positive patients (n = 1198) were on average younger and had more symptoms, a more acute disease onset, lower body mass index, and random C-peptide levels, but higher insulin needs, glycemia, and prevalence of ketonuria, HLA-DQ, and 5' insulin gene susceptibility genotypes (P < 0.001 vs. antibody-negative patients; n = 386). In antibody-positive patients, these characteristics did not differ according to HLA-DQ genotype. However, in antibody-negative subjects, we found that patients were younger (P = 0.001); had a lower body mass index (P < 0.001), higher insulin needs (P = 0.014), and amylasemia (P = 0.001); and tended to have a higher glycemia and lower C-peptide in the presence of susceptible HLA-DQ genotypes. Differences according to HLA-DQ genotype subsisted after careful age-matching. In conclusion, we found no relation between initial disease phenotype and HLA-DQ genotype in antibody-positive diabetic young adults. In contrast, antibody-negative patients displayed more type I-like features when carrying susceptible HLA-DQ genotypes known to promote the development of antibody-positive diabetes. The overrepresentation of these susceptibility genotypes in antibody-negative patients suggests the existence of an immune-mediated disease process with as yet unidentified immune markers in a subgroup of seronegative patients. [less ▲]Detailed reference viewed: 138 (5 ULg)
IA-2-autoantibodies complement GAD65-autoantibodies in new-onset IDDM patients and help predict impending diabetes in their siblings. The Belgian Diabetes Registry.
; ; et al
in Diabetologia (1997), 40(1), 95-9
IA-2 has been identified as an autoantigen that is recognized by immunoglobulins from insulin-dependent diabetic (IDDM) patients. Using a liquid phase radiobinding assay, we performed an IA-2-autoantibody ... [more ▼]
IA-2 has been identified as an autoantigen that is recognized by immunoglobulins from insulin-dependent diabetic (IDDM) patients. Using a liquid phase radiobinding assay, we performed an IA-2-autoantibody (IA-2-Ab) assay in 474 IDDM patients and 482 non-diabetic control subjects aged 0-3 years. IA-2-Ab were detected in 58% of the patients and 0.8% of control subjects. Their prevalence in patients was lower than that of islet cell autoantibodies (ICA; 73%) or glutamic acid decarboxylase (M(r) 65 kDa)-autoantibodies (GAD65-Ab; 82%) but higher than that of insulin autoantibodies (IAA; 42%). IA-2-Ab were more frequent in patients under age 20 years (70%) than between 20 and 40 years (45%; p < 0.001). In the whole IDDM group, 92% of patients were positive for at least one of the three molecular assays, which is higher than the positivity for the ICA assay (73%). Only 1% was negative in the molecular assays and positive in the ICA assay. IA-2-Ab levels were positively correlated with ICA titres (p < 0.001) and HLA DQ A1*0301-DQ B1*0.02 (p < 0.003) by multivariate analysis. In a group of 481 non-diabetic siblings (age 0-39 years) of IDDM patients only 7 were IA-2-Ab positive (1.5%). All seven were under age 20 years and positive for at least two other autoantibodies and for DQ A1*0301-DQB1*0302. Four of these seven developed IDDM during the 6-70-month follow-up period. The positive predictive value of IA-2-Ab (57%) was higher than that of ICA, GAD65-Ab or IAA alone, or in combination (< or = 20%) but these calculations are restricted by the relatively short observation period and the small number of cases. The only IA-2-Ab-negative case of pre-diabetes was also negative for IAA and GAD65-Ab, while it was strongly positive for ICA. In conclusion, IA-2-Ab show a high diagnostic specificity for IDDM and are predictive markers of impending diabetes in siblings of patients. In combination with other molecular antibody assays they may replace ICA testing in future. Our data also indicate that other autoantibodies than IA-2-Ab, GAD65-Ab and IAA contribute to ICA. [less ▲]Detailed reference viewed: 61 (1 ULg)