Is the process of beta-cell destruction in type 1 diabetes at time of diagnosis more extensive in females than in males?

OBJECTIVE: To evaluate sex differences in patients with insulin-dependent diabetes mellitus (type 1 diabetes) by comparing the integrated parameters of metabolic control at the time of clinical diagnosis and 3 months after intensive insulin therapy in pre-pubertal, pubertal and post-pubertal patients. DESIGN: A total of 331 consecutive patients with newly diagnosed type 1 diabetes were studied. The mean age of the group was 15 years (s.d. 8.1; range 5-23 years). Patients were stratified into three groups according to their age at disease onset: pre-pubertal (ages 5-9 years), pubertal (ages 10-18 years) and post-pubertal (ages 19-23 years). METHODS: Glycated haemoglobin (HbA(1c)), insulin dose and both basal and glucagon-stimulated C-peptide were evaluated at diagnosis and after 3 months of insulin therapy. RESULTS: We found that females diagnosed after puberty were those with the lowest basal C-peptide compared with males (P=0.005). No statistically significant differences were observed for other metabolic parameters. When the entire group was evaluated, females at the time of diagnosis showed significant lower body mass index (P=0.001), lower basal C-peptide (P=0.021) and higher HbA(1c) (P=0.023) and required more insulin than males (P<0.001). After 3 months of therapy, only a significantly greater dose of insulin was observed in females compared with males (P=0.001), with similar good metabolic control as assessed by HbA(1c). CONCLUSIONS: We conclude that the process of beta-cell destruction at diagnosis may be more extensive in post-pubertal females than in males. Moreover, after the introduction of insulin therapy, females and males show similar metabolic parameters, although females still require significantly more insulin than males to achieve good metabolic control, 3 months after diagnosis.

Association of DRB1*04-DQB1*0301 haplotype and lack of association of two polymorphic sites at CTLA-4 gene with Hashimoto's thyroiditis in an Italian population.

Hashimoto's thyroiditis (HT) is an autoimmune disease resulting from a complex interaction between genetic and environmental factors. The genetic loci conferring susceptibility need to be still defined. The aim of the present study was to determine whether Cytotoxic T-Lymphocyte-Associated Antigen-4 (CTLA-4), HLA DRB1, and DQB1 genes were associated to HT in an Italian population. We evaluated the allele distribution of the following loci: CTLA-4 exon 1 A49G dimorphism, which resulted in an amino acidic exchange (Thr/Ala) in the leader peptide, CTLA-4 3' microsatellite, HLA DRB1 and DQB1 in 126 patients with HT and in 301 control subjects from an Italian population (Lazio region). CTLA-4 exon 1 A49G dimorphism was typed by Polymerase Chain Reaction and Restriction Fragment Length Polymorphism (PCR-RFLP); CTLA-4 3' microsatellite alleles were defined using a fluorescence-based method. HLA DRB1 and DQB1 alleles were typed using a SSO reverse line blot method and a probeless procedure based on allele group-specific amplification followed by DNA heteroduplex analysis, respectively. Data were initially analyzed by chi2 test or Fisher's exact test. Multiple logistic regression analysis was then applied on factors with significant crude odds ratios and on CTLA-4 exon 1 A49G dimorphism to investigate their independent effects. The two polymorphic sites at CTLA-4 gene did not increase the risk for HT. The distribution of HLA DRB1 and DQB1 alleles did not show any significant difference between patients and controls, however, the DRB1*04-DQB1*0301 haplotype was significantly increased in patients. Other factors that increase the risk of disease were gender and age. Females showed approximately 18 times more risk than males; subjects older than 50 years had an odds ratio of 6.6. These data suggest that these two polymorphic sites at CTLA-4 do not play a major role in the susceptibility of the disease in an Italian population while female gender, age over 50 years, HLA DRB1*04-DQB1*0301 haplotype increase the risk of developing HT.

Intradermal skin test with diabetes specific antigens in patients with type 1 diabetes.

Cell mediated immune response in vitro to a number of antigens has been reported in patients with Type 1 diabetes. The aim of the present study was to develop an in vivo intradermal (delayed type hypersensitivity) skin test using antigens known to be recognized by lymphocytes of patients with Type 1 diabetes and to compare, where possible, the in vivo response to the in vitro T cell proliferation to the same antigens. The skin test was performed in the following group of patients: 55 with recent onset Type 1 diabetes; 16 patients with Type 1 diabetes of longer duration; 10 patients with autoimmune thyroid disease and 20 patients with Latent Autoimmune Diabetes in Adults (LADA). Type 1 diabetes specific antigens for the skin test included glutamic acid decarboxilase (GAD65), insulin and beta casein, whereas diabetes non specific antigens included tetanus toxoid, diphteria, proteus, tubercolin, streptococcus, and glycerol as control. A multitest device consisting of heads delivering intradermally 10 microl of solution containing the antigens was applied to the forearms; the specific antigens were injected in one forearm whereas the non specific antigens were injected in the other forearm. Reading of the reaction, which was considered positive in the presence of a nodule of 2 mm diameter was performed 48 h after the multitest application. The in vitro T cell response to diabetes specific antigens used in the multitest was studied using conventional proliferation assays in patients with recent onset Type 1 diabetes and in age matched normal subjects. Only recent onset Type 1 diabetes patients showed an in vivo positive response to GAD65, such response being detectable in 10 patients (18%). Two patients reacted also to beta casein and insulin, all other patient groups resulted negative but 2 patients with longer duration of Type 1 diabetes. There was no apparent link between the in vivo skin test and in vitro T cell proliferation to GAD65. We conclude that in vivo cell mediated immune reaction to GAD65, insulin and beta casein can be visualized in a minority of patients with recent onset Type 1 diabetes. Further studies are required to determine specificity and whether altering the dose can improve the sensitivity of the test.

The distribution of HLA class II susceptible/protective haplotypes could partially explain the low incidence of type 1 diabetes in continental Italy (Lazio region).

HLA class II is the primary susceptibility gene to type 1 diabetes and the analysis of HLA class II association could help to clarify the relative weight of genetic contribution to the incidence of the disease. Here we present an extensive typing for HLA class II alleles and their haplotypes in a homogenous population of type 1 diabetic patients (n=134) and controls (n=128) and in simplex (n=100) and multiplex families (n=50) from continental Italy (Lazio region). Among the various haplotypes tested, the DRB1*0301-DQA1*0501-DQB1*0201 was the most frequent found in type 1 diabetic patients and was transmitted in 82% of affected siblings, whereas DRB1*0402-DQA1*0301-DQB1*0302 appeared to have the highest odds ratio (10.4), this haplotype was transmitted in 96.3% of affected siblings, followed by DRB1*0405-DQA1*0301-DQB1*0302, DRB1*0405-DQA1*0301-DQB1*0201, DRB1*0401-DQA1*0301-DQB1*0302 and DRB1*0404-DQA1*0301-DQB1*0302. The following haplotypes showed a significant decreased transmission to diabetic siblings: DRB1*0701-DQA1*0201-DQB1*0303, DR2-DQA1*01-DQB1*0602, DR5-DQA1*0501-DQB1*0301. We suggest that the HLA DR/DQ haplotype/genotype frequencies observed could in part explain the low incidence of type 1 diabetes registered in Lazio region (8.1/100.000/year), for a number of reasons: i) the low frequency, in the general control population, of the most susceptible haplotypes and genotype for type 1 diabetes DRB1*0301-DQA1*0501-DQB1*0201 (14%), and DR4-DQA1*0301-DQB1*0302 (9%) and DRB1*0301-DQA1*0501-DQB1*0201/DR4-DQA1*0301-DQB1*0302 (0.8%) compared to other countries characterised by high incidence rate of the disease, Sardinia and Finland, respectively; ii) a significant lower ratio, in the control population, between the susceptible DRB1*0301-DQA1*0501-DQB1*0201 and the neutral DRB1*0701-DQA1*0501-DQB1*0201 haplotypes compared to the Sardinian population; iii) the high frequency of protection haplotypes/genotypes as the DR5-DQA1*0501-DQB1*0301, and DR5-DQA1*0501-DQB1*0301/DR5-DQA1*0501-DQB1*0301 very common in the control population of Lazio region and the DRB1*1401-DQA1*0101-DQB1*0503 haplotype.