Environmental factors and epidemiology of childhood type 1 diabetes / Környezeti hatások a gyermekkori kezdetu, 1-es típusú diabetes epidemiológiai változásainak hátterében.

Összefoglaló. A Nemzetközi Diabetes Szövetség (International Diabetes Federation, IDF) legutóbbi becslése szerint napjainkban több mint 600 000, 15 év alatti 1-es típusú cukorbeteg gyermek él a világon, az új esetek száma pedig évi 98 200-ra teheto. Az elmúlt évtizedekben az 1-es típusú diabetes incidenciája világszerte jelentosen nott ebben a korosztályban: Európában az 1989 és 2013 közötti periódusban átlagosan évi 3,4%-kal, ami 20 éven belül a betegek számának duplázódását vetíti elore a kontinensen. Az epidemiológiai vizsgálatok kezdete óta nyilvánvaló, hogy a gyermekkori kezdetu, 1-es típusú diabetes elofordulási gyakorisága széles határok között ingadozik, amit egyaránt befolyásolnak geográfiai és klímaviszonyok, etnikai és demográfiai hatások. Bár az 1-es típusú cukorbetegség kialakulása során az autoimmunitás primer kockázati tényezoje a genetikai háttér, mégsem a genetikai terheltség populációszintu fokozódása okozza az incidencia robbanásszeru növekedését, hanem a környezeti tényezoknek a betegség penetranciáját megváltoztató hatása. A környezeti hatások oki tényezokként, akcelerátorokként és védofaktorokként is hozzájárulhatnak mindehhez, sot akár a betegség patogenezisében egyszerre több ponton, több mechanizmussal is részt vehetnek. Ugyanakkor a nemzetközi kutatások ellenére a legnépszerubb háttérelméletek (például vírusinfekció, higiéniahipotézis, bélmikrobiom, átereszto bél, D-vitamin-hiány) máig nem szolgálnak kielégíto magyarázattal az epidemiológiai észlelések többségére (például földrajzi régiónként jelentosen eltéro incidenciaértékek, geográfiai "forrópontok", az új esetek megjelenésének szezonális ingadozása, az incidenciacsúcsok ciklicitása). Összefoglalónk célja a gyermekkori 1-es típusú diabetes epidemiológiájára vonatkozó aktuális adatok és háttérelméletek áttekintése. Orv Hetil. 2021; 162(1): 13-22. Summary. According to the latest report of the IDF (International Diabetes Federation), more than 600 000 children under the age of 15 years are living with type 1 diabetes in the world and the number of new cases is estimated to be 98 200 annually. In recent decades, a significant increase in the incidence has been observed globally: during 1989-2013, the annual rate of increase was 3.4% in Europe, suggesting a doubling in the number of patients within approximately 20 years on the continent. The wide variation in incidence has been well documented by epidemiological studies and influenced by geographical and climatic conditions, ethnic and demographic factors. Although the genetic background is the primary risk factor for beta-cell autoimmunity, such dynamic changes in incidence are more likely to be associated with the higher environmental pressure than the increase in genetic load at population level. Environmental factors can also contribute to the pathogenesis of type 1 diabetes as accelerators, causal or protective factors, moreover may even be involved at several points and with several mechanisms at the same time. However, despite the extensive international research on environmental factors, the most popular hypotheses associated with them (e.g., virus infections, hygiene hypothesis, intestinal microbiota, leaky gut, lack of vitamin D) have not yet provided a satisfactory explanation for most epidemiological observations (e.g., geographically significant variability of incidence rates, geographical "hotspots", seasonal fluctuations in new cases, cyclical trends of incidence peaks). In this article, recent data and hypotheses about the epidemiology of childhood type 1 diabetes are summarized. Orv Hetil. 2021; 162(1): 13-22.

[Community-acquired bacterial infections among type 2 diabetic and non-diabetic patients hospitalized on a general medical ward: a clinical comparison]. / 2-es típusú diabetesesek és nem cukorbetegek területen szerzett, belgyógyászati osztályos felvételt igénylo bakteriális infekcióinak klinikai összehasonlítása.

Introduction: Previous data showed bacterial infections among diabetic patients to be more serious and frequent, with higher mortality rates in comparison with non-diabetics. Recent investigations, however, are contradictory. Aim: The goal of our prospective, observational study was to compare patients hospitalized on a general medical ward due to community-acquired bacterial infections with type 2 diabetes mellitus (T2DM) to those of non-diabetics (K) by 1) infection localization, 2) spectrum of pathogens, 3) three-month mortality rates. Method: Patients were consecutively involved (T2DM: n = 205, K: n = 202). We characterized the infections, clinical parameters, mortalities of the two groups, and matched them to international data. Results: No difference regarding clinical details of the groups were found except for glycemic parameters and BMI. In the T2DM group the skin- and soft tissue- (37.1%), in the K patients respiratory infections (37.1%) were the most common, followed by urinary ones (31.2% and 31.7%, respectively). Skin- and soft tissue infection incidence among T2DM subjects were higher compared to international results (37.1% vs. 16%). Co-presence of Gram positive and Gram negative bacteria in the skin- and soft tissue infections (23/76 vs. 5/46, p = 0.0149), and polymicrobial origin in the urinary tract infections (34.0% vs. 15.1%, p = 0.0335) were found to be more frequent in T2DM than in K. No difference regarding mortality rates were detected. In T2DM the skin- and soft tissue while in the K group the respiratory infections had the most death counts. Conclusions: We found higher rates of skin- and soft tissue infections among T2DM patients hospitalized on a general medical ward compared to international data. In total we did not find difference regarding three-month mortality between the groups. Our results highlight the importance of primary prevention and shows its inadequacy concerning skin and soft tissue infections among type 2 diabetics in Hungary. Orv Hetil. 2019; 160(41): 1623-1632.

[Genetics of type 1 diabetes: present and future]. / Az 1-es típusú diabetes genetikája: jelen és jövo.

Over the past decades the majority of genetic research focused on common diseases, and remarkable results were obtained for exploring the genetic background of type 1 diabetes. The classic linkage analyses and the modern genome-wide association studies demonstrated that the genetic background is the primary risk factor for beta-cell autoimmunity while the progression to clinical onset could be triggered by the genetic factors, epigenetic modifications of gene expression and environmental factors together. The new system biology concept can help to understand the mechanisms underlying the immune-mediated beta-cell destruction by generating networks based on data from whole genome scans, fine mapping and gene expression studies to develop targeted prevention and therapeutic strategies. In this paper, we discuss the present understanding of genetic factors which could initiate beta-cell autoimmunity (i.e. define the aetiology) and the genetic and epigenetic factors which might contribute to the progression to clinical disease in individuals with autoantibodies (i.e. define the pathogenesis). Orv Hetil. 2017; 158(44): 1731-1740.

Lymphocyte activation in type 1 diabetes mellitus: the increased significance of Kv1.3 potassium channels.

Kv1.3 and IKCa1 potassium channels participate in the maintenance of calcium-influx during lymphocyte activation. Kv1.3 channels have a prominent role in specific T cell subsets, presenting a possible target for selective immunomodulation. We investigated the impact of Kv1.3 and IKCa1 channel inhibitors on calcium-influx characteristics in human T cells in type 1 diabetes mellitus. We isolated lymphocytes from 9 healthy and 9 type 1 diabetic individuals and measured the alteration of calcium-influx with flow cytometry in the Th1, Th2, CD4 and CD8 subsets after treatment of samples with specific channel inhibitors. Our results indicate an increased reactivity of type 1 diabetes lymphocytes, which is correlated to their increased sensitivity to Kv1.3 channel inhibition. However, the contribution of Kv1.3 channels to calcium flux is not exclusive for a specific lymphocyte subset as previous reports suggest, but is characteristic for each subset investigated. Therefore, the proposed inhibition of Kv1.3 channels as a novel therapeutic approach for the treatment of type 1 diabetes mellitus may have a major effect on overall lymphocyte function in this disease.

Association of hypoxia inducible factor-1 alpha gene polymorphism with both type 1 and type 2 diabetes in a Caucasian (Hungarian) sample.

BACKGROUND: Hypoxia inducible factor-1 alpha (HIF-1alpha) is a transcription factor that plays an important role in neo-vascularisation, embryonic pancreas beta-cell mass development, and beta cell protection. Recently a non synonymous single nucleotide polymorphism (g.C45035T SNP, rs11549465) of HIF-1alpha gene, resulting in the p.P582S amino acid change has been shown to be associated with type 2 diabetes (T2DM) in a Japanese population. Our aim was to replicate these findings on a Caucasian (Hungarian) population, as well as to study whether this genetic effect is restricted to T2DM or can be expanded to diabetes in general. METHODS: A large Caucasian sample (N = 890) was recruited including 370 T2DM, 166 T1DM and 354 healthy subjects. Genotyping was validated by two independent methods: a restriction fragment analysis (RFLP) and a real time PCR using TaqMan probes. An overestimation of heterozygotes by RFLP was observed as a consequence of a nearby SNP (rs34005929). Therefore genotyping results of the justified TaqMan system were accepted. The measured genotype distribution corresponded to Hardy-Weinberg equilibrium (P = 0.740) RESULTS: As the TT genotype was extremely rare in the population (0.6% in clinical sample and 2.5% in controls), the genotypes were grouped as T absent (CC) and T present (CT and TT). Genotype-wise analysis showed a significant increase of T present group in controls (24.0%) as compared to patients (16.8%, P = 0.008). This genetic effect was demonstrated in the separated samples of type 1 (15.1%, P = 0.020), and also in type 2 (17.6%, P = 0.032) diabetes. Allele-wise analysis gave identical results showing a higher frequency of the T allele in the control sample (13.3%) than in the clinical sample (8.7%, P = 0.002) with similar results in type 1 (7.8%, P = 0.010) and type 2 (9.1%, P = 0.011) diabetes. The odds ratio for diabetes (either type 1 or 2) was 1.56 in the presence of the C allele. CONCLUSION: We confirmed the protective effect of a rare genetic variant of HIF-1alpha gene against type 2 diabetes in a Caucasian sample. Moreover we demonstrated a genetic contribution of the same polymorphism in type 1 diabetes as well, supporting a possible overlap in pathomechanism for T2DM and a T1DM.

A detailed investigation of maternally inherited diabetes and deafness (MIDD) including clinical characteristics, C-peptide secretion, HLA-DR and -DQ status and autoantibody pattern.

BACKGROUND: This article presents a clinically characterization of the mitochondrial DNA mutation (A3243G) associated with maternally inherited diabetes and deafness (MIDD) syndrome in two families. METHODS: Six patients with MIDD and one mutation-positive relative with normal glucose tolerance (NGT) were examined. Fasting serum C-peptide was measured in all subjects and compared with controls having NGT (n = 14). C-peptide response to an intravenous glucose tolerance test (IVGTT) was investigated in the diabetic patients not treated with insulin (n = 3) and in the mutation-positive healthy individual and compared with the controls. RESULTS: The A3243G heteroplasmy value varied between 5 and 30%. All A3243G carriers had HLA-DR1-DQ5 haplotype, and either the -DQ5 or the -DQ6 allele. The fasting and the serum C-peptide levels at 120 min during the IVGTT did not differ between the A3243G carriers and the controls. A missing first phase and a decreased total C-peptide response was detected in the mutation-positive diabetics compared with controls (p < 0.0001). The same abnormality was found in the A3243G carrier with NGT. Circulating islet cell antibody (ICA) was present in three patients with MIDD. Glutamic acid decarboxylase (GAD), tyrosine phosphatase-like protein IA-2 (IA-2) and mitochondrial antibodies were missing. The diagnosis of MIDD was delayed in each case. CONCLUSIONS: A missing first phase and a decreased total C-peptide response during an IVGTT was characteristic for the A3243G mutation. The fasting C-peptide level of the carriers did not differ from the controls. Circulating ICA was present in some patients, but GAD, IA-2 and mitochondrial antibodies were absent. All subjects had HLA-DR1-DQ5 haplotype, and either -DQ5 or -DQ6 alleles.

[Effectiveness of cardiometabolic risk reduction in patients with type 1 diabetes mellitus]. / A kardiometabolikus kockázati tényezôk kezelésének eredményessége 1-es típusú diabetesben szenvedôk körében.

UNLABELLED: The attainment and maintenance of therapeutic goal of cardiovascular risk factors are of great clinical importance. The effectiveness of cardiovascular risk management is not well characterized during regular care of patients with type 1 diabetes mellitus. AIM: The aim of the study was to estimate the effectiveness of cardiovascular risk management in type 1 diabetic patients. METHODS: Adult patients with type 1 diabetes mellitus (n = 533; 256 men, 277 women; age: 35.6 +/- 11.6 years; duration of diabetes: 18.0 +/- 11.1 years; x +/- SD) were consecutively enrolled from 11 diabetes outpatient departments. Data on medical history, actual treatment, anthropometric and laboratory parameters as well as actual blood pressure were registered, while eating and smoking habits, education level and physical activity were evaluated by standardized questionnaires. The treating goal was set according to the national guideline which corresponds to the current international task force. RESULTS: Of 533 patients, the body mass index target level (< 25 kg/m 2 ) was achieved by 295 (55.5%) patients. Ideal waist circumference (< 80 cm for women and < 94 cm for men) was measured in 140 (50.5%) and in 165 (63.7%) patients, respectively. Optimal glycaemic control (HbA 1c level < 6.5%) was documented in 45 (8.4%) patients. Lipid lowering drugs (statins, fibrates or ezetimibe) were used by 130 patients, among which 53.1% reached the target triglyceride level, 71.5% the target HDL-cholesterol and 27.8% the target LDL-cholesterol levels. Taking the lipid target values together, only 23 (17.7%) patients were at goal. Antihypertensive drugs were used by 173 patients among which 29.5% reached the systolic and 34.8% the diastolic target values (< 130/80 mmHg). Regarding smoking habits, 94 (17.7%) patients were current smokers and 102 (19.2%) ex-smokers. CONCLUSIONS: The attainment of therapeutic goal of cardiovascular risk factors proved to be difficult in a substantial part of patients. Further efforts are needed for attaining and maintaining the established goal of cardiovascular risk management during regular care of adult patients with type 1 diabetes mellitus.

Glutathione S-transferase enzyme polymorphisms in a Hungarian myelodysplasia study population.

GSTM1, GSTT1 and GSTP1 Ile105Val that are members of the GST gene family encode for Phase II drug/xenobiotic metabolizing enzymes, primarily with detoxifying function, and are polymorphic in humans. GSTM1 and GSTT1 homozygous deletion genotypes do not express the enzymes. It has been hypothesised that individuals with homozygous deletion of the GSTM1 and/or GSTT1 gene may have lower detoxification capacity towards genotoxic agents therefore those individuals may be at increased risk of myelodysplastic syndrome which is a preleukemic condition. Genetic polymorphism of GSTM1, GSTT1 and GSTP1 Ile105Val was investigated in a case-control study in a Hungarian patient population comprising 86 patients with myelodysplastic syndrome and 99 hospital-based controls. There were no statistically significant differences between cases and controls for the GSTM1, GSTT1 and GSTP1 Ile105Val genotype frequencies for any of the three genes separately and in various combinations. This suggests that these genetic polymorphisms may not be strong risk factors, if any, for myelodysplastic syndrome.

[Clinical symptoms and treatment of cervicofacial actinomycosis. Literature survey and case report]. / Az actinomycosis cervicofacialis klinikai jellemzoi es korszeru terápiája. Irodalmi osszefoglaldó es esetközlés.

Actinomycosis is a chronic, specific inflammation which is characterized by suppuration, abscess formation, tissue fibrosis and granuloma formation. Actinomycosis has three main forms (cervicofacial, which is the most frequent, approximately 60%, pulmonary and abdominal), but other regions of the body can be involved, too (e.g. neck, ovaries, bones), that is why its differential diagnosis becomes more and more relevant. Regarding its treatment, the majority of authors recommends the combination of surgical and antibiotic treatment. The authors of this article present a typical case of cervicofacial actinomycosis, in which the authors used the combination of surgical and antibiotic treatment. As a result of the treatment the healing process was completed successfully and without complications.

Frequency of carriers of 8.1 ancestral haplotype and its fragments in two Caucasian populations.

Within the human MHC region larger stretches of conserved DNA, called conserved ancestral haplotypes exist. However, many MHC haplotypes contain only fragments of an ancestral haplotype. Little is known, however, on relative distribution of the ancestral haplotypes to their fragments. Therefore we determined the frequency of carriers of the whole ancestral haplotype 8.1 (AH8.1) and its fragments in 127 healthy Hungarian people, 101 healthy Ohioian females, and in nine Hungarian families. The HLA-DQ2, HLA-DR3(17), RAGE -429C allele, the mono-S-C4B genotype, the HSP70-2 1267G allele and the TNF -308A (TNF2) allele were used as markers of the AH8.1. Frequency of carriers of the whole AH8.1 and its fragments was similar in the both populations. 18% of the subjects carried the whole AH8.1 in at least one chromosome, while 17-20%, 36-39%, and 24-29%, respectively carried two or three constituents of the haplotype, only one constituent or none of them. Similar results were obtained in the family study. In addition, marked differences were found in the relationship of the constituents' alleles to the whole AH8.1. In both populations, 29%, 50-59%, 52-56% and 76-96%, respectively of the carriers of HSP70-2 1267G, RAGE-429C, TNF2, and mono-S carriers carried the whole 8.1 haplotype. These findings may have important implications for studies of the disease associations with different MHC ancestral haplotypes.

The HLA 8.1 ancestral haplotype is strongly linked to the C allele of -429T>C promoter polymorphism of receptor of the advanced glycation endproduct (RAGE) gene. Haplotype-independent association of the -429C allele with high hemoglobinA1C levels in diabetic patients.

Previously we reported on strong linkage disequilibrium (LD) between the mono-S-C4B-RCCX module (mono-S) and the TNF2 allele (both known constituents of the 8.1 ancestral haplotype (8.1 AH)) in two Caucasian populations. The gene for the receptor of advanced glycation endproducts (RAGE) is encoded between the RCCX module and the HLA class II genes in the central MHC region. In order to assess the relationship between the promoter polymorphisms of the RAGE gene and the 8.1 AH, we performed a family study in eight informative families affected with type 1 diabetes mellitus; haplotypes of a RAGE promoter SNP (-429T>C) with the HLA-DQ2, -DR-3(17) and TNF2 alleles, as well as the mono-S genotype were determined. A similar analysis was performed in 82 unrelated patients with type 1 diabetes mellitus, and in unrelated healthy individuals of three different Caucasian populations (Hungarians, Ohioian females, Icelandics). In the diabetic patients clinical correlations were also investigated. Out of the 32 paternal and maternal chromosome 6 from the eight families, 15 different MHC haplotypes were found. Haplotypes containing at least three of the known constituents of the 8.1 AH (HLA-DQ2, -DR17, mono-S, TNF2) were always linked to the RAGE -429C allele. The RAGE -429C allele exhibited highly significant (p<0.0001) LD coefficients to known constituents of the 8.1 AH both in healthy persons and patients with type 1 diabetes. In the group of patients with diabetes we found significantly (p=0.013) higher maximal hemoglobinA1C concentration in the carriers of the RAGE -429C allele, this trait, however was not linked to the 8.1 AH. Our present findings indicate that the RAGE -429C allele can be considered as a candidate member of the 8.1 AH. The results also reveal a spectrum of recombinant MHC haplotypes in addition to the conserved ancestral haplotypes.

Effect of heat shock protein peptide DiaPep277 on beta-cell function in paediatric and adult patients with recent-onset diabetes mellitus type 1: two prospective, randomized, double-blind phase II trials.

BACKGROUND: Aim of this trial was to test whether heat shock protein peptide DiaPep277 treatment in adult and paediatric patients with recent-onset type 1 diabetes (T1D) is safe and whether it can preserve endogenous insulin production. METHODS: Two studies were performed in a prospective, multicentre, double-blind, placebo-controlled trial. Fifty adult (study p520, aged 16-44 years) and 49 paediatric patients (study p521, 4-15 years) with recent-onset T1D were treated subcutaneously at four different time points with 0.2 mg or 1.0 mg DiaPep277 versus placebo and followed for 18 months. Adult patients were treated with 0.2 mg, 1.0 mg or 2.5 mg DiaPep277 versus placebo. Stimulated C-peptide served as readout for functional beta-cell-mass. RESULTS: DiaPep277-treatment was not associated with severe side effects. No differences were found in placebo and DiaPep277 treated groups. In adults, a modest trend towards better maintenance of beta-cell function was observed in the 0.2 mg and 1.0 mg group, while there was significant loss of stimulated C-peptide in the placebo and 2.5 mg group. Paediatric patients with low HLA risk showed stable C-peptide levels until 13 months upon treatment with 1 mg DiaPep277. Despite similar stimulated C-peptide levels at baseline, children exhibited a more pronounced loss of beta-cell function over 18 months than adults (p = 0.0003). CONCLUSION: Administration of DiaPep277 seems safe and may have beneficial effects on C-peptide levels over time in some patients with T1D, but this finding was not accompanied by reduced HbA1c or insulin requirement. Studies with more patients and longer follow-up are needed to further study the effect of DiaPep277.

[Diagnosis of diabetes mellitus]. / A diabetes mellitus diagnosztikája.

Beside the clinical diagnosis of diabetes mellitus based on the measurement of blood glucose level, these days, the etiologic classification of the disease comes to the forefront. Genetic analysis (HLA typing, searching for glucokinase gene and mitochondrial gene mutations), immunologic examination (determination of islet specific autoantibodies) and measurement of the insulin secretory capacity help the etiologic classification. The most important result of classification is the discovery of the slowly progressive form of type 1 diabetes mellitus (formerly latent autoimmune diabetes in adults). Another direction of diagnostic procedures is the prediction of the disease in nondiabetic population. The prediction of type 1 diabetes is not specific enough at present, but that of type 2 diabetes can be done easily.

Overrepresentation of the N363S variant of the glucocorticoid receptor gene in patients with bilateral adrenal incidentalomas.

CONTEXT: Some variants of the glucocorticoid receptor (GR) gene have been found to alter glucocorticoid sensitivity and have been associated with altered metabolic profiles. OBJECTIVE: The objective of the study was to examine whether N363S and ER22/23K variants of the GR gene may be associated with the development of adrenal incidentalomas and whether these variants may contribute to metabolic abnormalities frequently present in these patients. DESIGN, SETTING, AND PATIENTS: The study included 99 patients with unilateral and 44 patients with bilateral adrenal incidentalomas, 102 population-matched control subjects, and 100 patients with type 2 diabetes mellitus. MAIN OUTCOME MEASURES: Metabolic and hormonal parameters and GR gene variants were determined. RESULTS: When compared with control subjects, the carrier frequency for the N363S variant was markedly and significantly higher in patients with bilateral (7.8 vs. 20.5%, P < 0.05) but not in those with unilateral incidentalomas (7.1%) or in patients with type 2 diabetes (13.0%). Type 2 diabetes occurred more frequently in patients with bilateral, compared with those with unilateral incidentalomas (40.9 vs. 22.2%, P < 0.05). In patients with bilateral incidentalomas, a significant association of the N363S variant with impaired glucose homeostasis but not with body mass index, hypertension, hyperlipidemia, or history of coronary artery disease was found. The carrier frequency of the ER22/23EK variant was similar in all groups, and this variant failed to show any association with metabolic abnormalities. CONCLUSION: These results suggest that the N363S variant of the GR gene may play a role in the pathogenesis of bilateral adrenal incidentalomas, although the mechanism still remains to be investigated.

Similar genetic features and different islet cell autoantibody pattern of latent autoimmune diabetes in adults (LADA) compared with adult-onset type 1 diabetes with rapid progression.

OBJECTIVE: To compare the clinical parameters, C-peptide levels, pattern of islet cell-specific autoantibodies, and prevalence of predisposing genotypes in subjects with latent autoimmune diabetes in adults (LADA) and those with adult-onset type 1 diabetes with rapid progression. RESEARCH DESIGN AND METHODS: We evaluated the clinical parameters, C-peptide levels, and islet cell-specific autoantibodies in 54 LADA, 57 adult-onset type 1 diabetic, and 190 type 2 diabetic patients. Islet cell autoantibodies were also compared between subgroups of newly diagnosed patients with LADA and those with newly diagnosed adult-onset and childhood-onset type 1 diabetes. The genetic study was performed in subjects with LADA and those with adult-onset type 1 diabetes in comparison with a control population. RESULTS: There were no differences in the clinical parameters between LADA and adult-onset type 1 diabetes. Patients with LADA had lower BMI (P < 0.0001), waist-to-hip ratio (0.0029), total cholesterol (P = 0.001), and triglycerides (P = 0.001); higher HDL cholesterol levels (P < 0.0001); and lower prevalence of hypertension (P = 0.0028) compared with patients with type 2 diabetes. C-peptide levels were similar at onset (P = 0.403) but decreased less rapidly in LADA than in adult-onset type 1 diabetes (P = 0.0253). Single-autoantibody positivity was more often seen in LADA than in type 1 diabetes (P = 0.0001). The prevalence of predisposing HLA-DQB1*0302, -DR4, -DR3, and -DR3/DR4 genotypes and the DR4-DQB1*0302 haplotype were increased in both LADA and adult-onset type 1 diabetic subjects compared with the control population. There were no differences in the frequencies of these risk alleles and haplotypes between the two patient groups. CONCLUSIONS: Subjects with LADA had clinical characteristics similar to those with adult-onset type 1 diabetes with rapid progression. C-peptide levels did not differ at onset but decreased less rapidly in LADA. Patients with LADA rather had single islet cell-specific autoantibody positivity. The prevalence of HLA-DQB1*0302, -DR4, -DR3, and -DR3/DR4 risk alleles and the DR4-DQB1*0302 high-risk haplotype did not differ in the two forms of autoimmune diabetes.

Differences in the genetic background of latent autoimmune diabetes in adults (LADA) and type 1 diabetes mellitus.

OBJECTIVES: According to the recent classification of diabetes mellitus the Latent Autoimmune Diabetes in Adults (LADA) belongs to the group of type 1 autoimmune diabetes, as a slowly progressive form. Our aim was to determine (i) the prevalence of HLA-DRB1 and DQB1 genotypes, and (ii) to determine the tumor necrosis factor (TNF) alpha promoter polymorphism at position -308 (the G-->A substitution, designated the TNF2 allele) in patients with type 1 diabetes and with LADA compared with the healthy population. METHODS: The major histocompatibility complex (MHC) II genotypes and the TNF alpha promoter polymorphism were determined by PCR method. We examined 69 type 1 diabetic and 42 LADA patients. As control samples of 336 cadaver kidney donors and 138 volunteers were used. RESULTS: Both type 1 diabetes mellitus and LADA were positively associated with the DRB1*04-DQB1*0302 (DR4/DQ8) haplotype (P=0.00001, and P=0.0005, respectively), and negatively associated with the DRB1*11-DQB1*0301 (DR11/DQ7) haplotype (P=0.00006, and P=0.007, respectively) compared with control population. There were differences between the two disease entities in the frequency of the DRB1*03-DQB1*02 (DR3/DQ2) haplotype (P=0.00008 vs. P=0.177) compared with control group. The presence of the TNF2 allele was significantly lower in LADA than type I diabetes (P=0.022) or control group (P=0.017). CONCLUSION: Our findings indicate that there are marked differences in the genetic background of type 1 diabetes and LADA. The low presence of TNF2 allele (known to be associated with high amount of TNF alpha production) in LADA could be one of the factors responsible for the relatively slow progression.