Increased risk of diabetes among relatives of female insulin-treated patients diagnosed at 15-34 years of age

Extended family history of type 1 diabetes and phenotype and genotype of newly diagnosed children

OBJECTIVE

To determine the frequency of newly diagnosed diabetic children with first- and second-degree relatives affected by type 1 diabetes and to characterize the effects of this positive family history on clinical markers, signs of β-cell autoimmunity, and HLA genotype in the index case.

RESEARCH DESIGN AND METHODS

Children (n = 1,488) with type 1 diabetes diagnosed under 15 years of age were included in a cross-sectional study from the Finnish Pediatric Diabetes Register. Data on family history of diabetes and metabolic decompensation at diagnosis were collected using a questionnaire. Antibodies to β-cell autoantigens (islet cell antibodies, insulin autoantibodies, GAD antibodies, and antibodies to the islet antigen 2 molecule) and HLA genotypes were analyzed.

RESULTS

A total of 12.2% of the subjects had a first-degree relative with type 1 diabetes (father 6.2%, mother 3.2%, and sibling 4.8%) and 11.9% had an affected second-degree relative. Children without affected relatives had lower pH (P < 0.001), higher plasma glucose (P < 0.001) and β-hydroxybutyrate concentrations (P < 0.001), a higher rate of impaired consciousness (P = 0.02), and greater weight loss (P < 0.001). There were no differences in signs of β-cell autoimmunity. The familial cases carried the HLA DR4-DQ8 haplotype more frequently than sporadic cases (74.0 vs. 67.0%, P = 0.02).

CONCLUSIONS

When the extended family history of type 1 diabetes is considered, the proportion of sporadic diabetes cases may be reduced to <80%. A positive family history for type 1 diabetes associates with a less severe metabolic decompensation at diagnosis, even when only second-degree relatives are affected. Autoantibody profiles are similar in familial and sporadic type 1 diabetes, suggesting similar pathogenetic mechanisms.

Long-term detrimental consequences of the onset of type 1 diabetes on annual earnings--evidence from annual registry data in 1990-2005

AIMS/HYPOTHESIS

Young adults in the early stages of their participation in the labour market may be particularly vulnerable to the effects of onset of a chronic disease. Our aim was to quantify the consequences of the onset of type 1 diabetes in young adults on annual earnings, using individual-level longitudinal data before and after the onset of diabetes.

METHODS

The Econ-DISS database contains annual socioeconomic information for 1990-2005 from Statistics Sweden. Econ-DISS includes data for persons with diabetes onset at the age of 15-34 years between 1983 and 2005, registered in the national Diabetes Incidence Study in Sweden (DISS) database, and for controls. Considering the onset of type 1 diabetes as an unanticipated and significant life event, we compared the progression of annual earnings for 3,650 cases born between 1949 and 1970 before and after onset of diabetes with that of 14,629 controls. Possible confounders--education, participation in the labour market, sick leave and parental education--were analysed.

RESULTS

We found no differences between the groups in annual earnings or participation in the labour market before onset of diabetes. After onset, persons with type 1 diabetes gradually lagged behind the controls. Their median annual earnings were lower in each year from 1995 to 2005 (p < 0.01). The difference in 2005 was euro (EUR) 1,411 (5.3%). Controlling for confounders, duration of type 1 diabetes > or = 10 years was associated with 4.2% (men) and 8.1% (women) lower average annual earnings for persons with upper secondary education only who were active in the labour market.

CONCLUSION/INTERPRETATION

The onset of type 1 diabetes in young adults has long-term detrimental consequences on earnings that cannot be attributed to confounders.

Immunology of beta-cell destruction

The pancreatic islet beta-cells are the target for an autoimmune process that eventually results in an inability to control blood glucose due to the lack of insulin. The different steps that eventually lead to the complete loss of the beta-cells are reviewed to include the very first step of a triggering event that initiates the development of beta-cell autoimmunity to the last step of appearance of islet-cell autoantibodies, which may mark that insulitis is about to form. The observations that the initial beta-cell destruction by virus or other environmental factors triggers islet autoimmunity not in the islets but in the draining pancreatic lymph nodes are reviewed along with possible basic mechanisms of loss of tolerance to islet autoantigens. Once islet autoimmunity is established the question is how beta-cells are progressively killed by autoreactive lymphocytes which eventually results in chronic insulitis. Many of these series of events have been dissected in spontaneously diabetic mice or rats, but controlled clinical trials have shown that rodent observations are not always translated into mechanisms in humans. Attempts are therefore needed to clarify the step 1 triggering mechanisms and the step to chronic autoimmune insulitis to develop evidence-based treatment approaches to prevent type 1 diabetes.