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Environmental, maternal influences alter type 1 diabetes risk in children

D’Angeli MA. Arch Pediatr Adolesc Med. 2010;164:732-738.

Childhood-onset type 1 diabetes has been linked to environmental factors associated with decreased antigenic exposure early in life and to maternal obesity, rather than infant characteristics.

A population-based, case-control study identified 1,852 children aged 19 years and younger. All were hospitalized for type 1 diabetes in Washington between 1987 and 2005. Randomly selected controls (n=7,408) were matched based on year of birth.

A number of social and physical exposures were considered in the study, both for mother and child. Maternal factors included age, race/ethnicity, educational level, marital status, Medicaid, BMI, pre-pregnancy weight, previous births, prenatal care and cesarean delivery. Infant factors included birth weight, size for gestational age and gestational age.

The presence of type 1 diabetes was negatively associated with several factors, such as multiple older siblings (three or more: OR=0.56; 95% CI, 0.45-0.70); indicators of lower economic status (for unmarried mothers: OR=0.79; 95% CI, 0.69-0.91); and possession of Medicaid insurance (OR=0.67; 95% CI, 0.58-0.77).

In addition, maternal BMI was linked to the risk for diabetes, particularly in mothers whose BMI was 30 or higher (OR=1.29; 95% CI, 1.01-1.64). Risk was also greater in mothers whose pre-pregnancy weight was 200 lb or more (OR=1.62; 95% CI, 1.22-2.14).

“These results are consistent with the overload hypothesis that suggests that overnutrition, whether prenatally or postnatally, may cause overload or stress to the developing pancreas, which subsequently predisposes to type 1 diabetes,” the researchers wrote.

When the researchers examined infant characteristics, they found no significant association with risk for diabetes.

“A better understanding of the nongenetic risk factors associated with type 1 diabetes will help inform prevention programs and potentially reduce the burden of this devastating disease,” the researchers concluded.

Genes, predominantly (HLA DR/DQ haplotypes), are likely necessary but not sufficient for the development of type 1 diabetes. However, increases in the worldwide incidence of type 1 diabetes over the last 50 years implicate changing environmental factors and, hence, pursuit of putative environmental triggers. In an effort to provide support for several environment-based hypotheses, D’Angeli et al performed a case-control study of children with and without diabetes from Washington state. Results of their study support the concepts that maternal socioeconomic and demographic factors (age, race/ethnicity, education, marital status, insurance type, etc.) and physical attributes such as BMI may affect risk for type 1 diabetes. While the conclusions of this study are somewhat limited by its case-control design, the results are intriguing and support previous observations. Ongoing prospective studies such as The Environmental Determinants of Diabetes in Youth (TEDDY) study should, with time, provide the critical information needed to definitively answer questions related to environmental risk and type 1 diabetes.

–Michael Haller, MD, and Desmond Schatz, MD

Assistant Professor of Pediatric Endocrinology,

Professor, Associate Chairman of Pediatrics and Medical Director, Diabetes Center,

Both at University of Florida

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