Interbirth interval is associated with childhood type 1 diabetes risk.

Short interbirth interval has been associated with maternal complications and childhood autism and leukemia, possibly due to deficiencies in maternal micronutrients at conception or increased exposure to sibling infections. A possible association between interbirth interval and subsequent risk of childhood type 1 diabetes has not been investigated. A secondary analysis of 14 published observational studies of perinatal risk factors for type 1 diabetes was conducted. Risk estimates of diabetes by category of interbirth interval were calculated for each study. Random effects models were used to calculate pooled odds ratios (ORs) and investigate heterogeneity between studies. Overall, 2,787 children with type 1 diabetes were included. There was a reduction in the risk of childhood type 1 diabetes in children born to mothers after interbirth intervals <3 years compared with longer interbirth intervals (OR 0.82 [95% CI 0.72-0.93]). Adjustments for various potential confounders little altered this estimate. In conclusion, there was evidence of a 20% reduction in the risk of childhood diabetes in children born to mothers after interbirth intervals <3 years.

HLA class II alleles and haplotypes in Lithuanian children with type 1 diabetes and healthy children (HLA and type 1 diabetes).

OBJECTIVE: Type 1 diabetes mellitus is a slowly progressive autoimmune disease. The genetic background of type 1 diabetes mellitus is polygenic with the major disease locus located in the human leukocytes antigen (HLA) region. High risk and protective alleles, haplotypes, and genotypes have been determined in Lithuanian children with type 1 diabetes mellitus and healthy children. MATERIAL AND METHODS: In this case-control study, 124 children with diabetes (55 males and 69 females; mean age, 9.2±3.9 years) were tested for HLA class II and compared with 78 healthy controls (43 males and 35 females; mean age, 10.8±3.4 years; range, 0-15 years). HLA DRB1, DQA1, and DQB1 alleles were genotyped using a polymerase chain reaction. RESULTS: T1D risk-associated haplotypes (DR4)-DQA1*0301-DQB1*0302, (DR3)-DQA1*0501-DQB1*0201, and (DR1)-DQA1*0101-04-DQB1*0501 were more prevalent among children with diabetes than controls (50.0%, 41.1%, and 37.9% vs. 10.3%, 5.1%, and 24.4%, P<0.001). The haplotypes (DR4)-DQA1*0301-DQB1*0302 and (DR3)-DQA1*0501-DQB1*0201 increased T1D risk by 8.75 and 12.93 times, respectively (P<0.001). Protective haplotypes (DR2)-DQA1*0102-B1*0602, (DR11/12/13)-DQA1*05-DQB1*0301, and (DR13)-DQA1*0103-DQB1*0603 were significantly more prevalent among controls than children with diabetes (25.6%, 33.3%, 19.2% vs. 0%, 3.2%, 0%; P<0.001). These frequencies are quite similar to those from neighbor countries with varying incidence of type 1 diabetes mellitus. CONCLUSIONS: HLA class II haplotypes associated with type 1 diabetes mellitus positively or negatively were the same in Lithuanian children as in other European Caucasian populations. Differences in incidence and clinical manifestations of type 1 diabetes might be due to different environmental factors and/or lifestyle.

Environmental risk factors in prediction of childhood prediabetes.

OBJECTIVE: The damage of beta cells occurs during the asymptomatic prodromal period called prediabetes before onset of diabetes mellitus. It is characterized by the presence of islet cell autoantibodies (ICAs). The aim of this study was to find out what environmental factors predict ICA seroconversion in healthy schoolchildren in Lithuania. MATERIAL AND METHODS: Sera from 3053 nondiabetic schoolchildren living in Lithuania were investigated for ICAs. ICAs were measured in undiluted sera by indirect immunofluorescence method. All ICA-positive and randomly selected ICA-negative children were invited to participate in the study. Response rate in the families of ICA-positive children was 100% and in ICA-negative-76.5%. Data from 13 ICA-positive and 199 ICA-negative schoolchildren were included in the analysis. Information on the environmental factors was collected via questionnaires. RESULTS: Proportions of breastfed children were similar in ICA-positive and ICA-negative schoolchildren. Full cow's milk was introduced at one month of age or earlier more often in ICA-positive than ICA-negative schoolchildren (8.3% and 1.1%, respectively; P=0.05). Cereal before 3 months of age was introduced more often in ICA-positive than ICA-negative schoolchildren (7.7% and 0.5%, respectively; P=0.01). The mothers of cases took medicine during pregnancy more often than mothers of controls did (61.5% and 14.1%, respectively; P<0.001). More than half (53.8%) of ICA-positive children lived in homes where family members were smoking indoors, while this was recorded only for 26.6% of controls (P=0.04). CONCLUSIONS: Early introduction of cow's milk and cereal, the intake of medicine during pregnancy, and indoor smoking of family members are risk factors that predict the development of prediabetes among Lithuanian children.

Higher prevalence of autoantibodies to insulin and GAD65 in Swedish compared to Lithuanian children with type 1 diabetes.

We compared the prevalence of beta-cell autoantibodies and genetic risk factors in Sweden and Lithuania. Ninety-six patients from Sweden and 96 from Lithuania matched for age and gender (1-15 years old, median age 9.0 years) were included. We analyzed autoantibodies to insulin (IAA), glutamic acid decarboxylase (GADA) and the protein tyrosine phosphatase like IA-2 (IA-2A) as well as risk-associated polymorphisms of HLA, insulin and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) genes. The frequency of patients positive for IAA and GADA was higher in Sweden than in Lithuania (p = 0.043 and 0.032). The differences remained even when the patients were matched for HLA, insulin and CTLA-4 risk genotypes. Patients with low levels of IAA had higher levels of HbA1c and ketones at diagnosis. The frequency of the risk haplotype DR4-DQ8 was higher in Swedish than in Lithuanian patients (p = 0.004), as well as the high-risk combination of DR4-DQ8 and DR3-DQ2 haplotypes (p = 0.009). Our results suggest that autoimmune process against insulin and GAD(65) is more common at diagnosis in children in areas with high incidence of type 1 diabetes (T1D), independent of genetic risk markers. Furthermore, the disease in patients with insulin autoantibodies seems to be clinically milder.

Longer breastfeeding is an independent protective factor against development of type 1 diabetes mellitus in childhood.

BACKGROUND: Early weaning diet, early introduction of breast milk substitution and cow's milk have been shown to increase the risk of type 1 diabetes later in life. It is also shown that older maternal age, maternal education, preeclampsia, prematurity, neonatal illness and neonatal icterus caused by blood group incompatibility, infections and stress might be risk factors for type 1 diabetes. We aimed to determine whether early nutrition is an independent risk factor for diabetes despite other life events. METHODS: Data from 517 children (268 boys and 249 girls) in south-east of Sweden and 286 children (133 boys and 153 girls) in Lithuania in the age group of 0 to 15 years with newly diagnosed type 1 diabetes mellitus were included into analysis. Three age- and sex-matched healthy controls were randomly selected. Response rate in control families in Sweden was 72.9% and in Lithuania 94.8%. Information was collected via questionnaires. RESULTS: Exclusive breastfeeding longer than five months (odds ratio 0.54, 95% confidence interval 0.36-0.81) and total breastfeeding longer than 7 (0.56, 0.38-0.84) or 9 months (0.61, 0.38-0.84), breastfeeding substitution that started later than the third month (0.57, 0.33-0.98) among Swedish children 5 to 9 years old and later than the seventh month (0.24, 0.07-0.84) among all Swedish children is protective against diabetes when adjusted for all other above-listed risk factors. In Lithuania, exclusive breastfeeding longer than two months in the age group of 5 to 9 years is protective (0.58, 0.34-0.99) when adjusted for other factors. CONCLUSIONS: Longer exclusive and total breastfeeding appears as an independent protective factor against type 1 diabetes.

Inheritance of MHC class II genes in Lithuanian families with type 1 diabetes.

Type 1 diabetes mellitus (DM) is caused by genetic and environmental factors. Twice as many fathers as mothers of children with type 1 DM have the disease. The reason for the differences remains unclear. We looked at the transmission rates of diabetes-related alleles from parents to children with diabetes. All children with newly diagnosed type 1 DM from August 1, 1996 to August 1, 2000, aged 0 to 15 years, in Lithuania were invited to participate. Blood samples for full genetic analysis were available from 125 families. HLA DQA1, DQB1, and DRB1 typing was done on DNA extracted from peripheral blood, by polymerase chain reaction amplification, manual dot-blotting onto nylon membranes, synthetic sequence-specific oligonucleotide probe 3'-end labeling with (32)P-dCTP, and hybridization, followed by stringency washes, autoradiography, and allele calling. Frequency of diabetes risk-related alleles DQB1*0302, DQA1*0201, DR4, and DR3 was less prevalent among Lithuanian than among Swedish children with type 1 DM. Transmission rates of DR4-DQB1*0302-DQA1*0301 and DR3-DQB1*0201-DQA1*0501 haplotypes from parents were higher than expected: chi(2) (TDT) 30.56, p < 0.0001, and chi(2) (TDT) 11.26, p = 0.0008, respectively. DQB1*0302 and DR4 were significantly more frequently transmitted from both parents, but DR3 was transmitted more frequently only from mothers. Any of these alleles had similar frequencies among female and male offspring. We conclude that, besides DR4-DQB1*0302-DQA1*0301 and DR3-DQB1*0201-DQA1*0501, there are other inherited alleles that determine risk for type 1 DM among children in Lithuania. Fathers might transfer other alleles of disease susceptibility in higher frequency or mothers might provide a protective environment during pregnancy, which results in higher risk to offspring of fathers than mothers to develop diabetes.