Type 1 Diabetes Linked to Lower Fertility

Steven Fox

February 29, 2012

February 29, 2012 — Significantly fewer children are born to couples when 1 partner has type 1 diabetes, according to results from a cross-sectional study conducted in Germany.

The study was published online February 23 in Diabetic Medicine.

The authors, led by Andreas Holstein, MD, from the First Department of Medicine, Lippe-Detmold Hospital, Detmold, Germany, note that there are only limited data regarding the fertility of people with type 1 diabetes, and that this is especially true for men. "Therefore, the aim of this study was to assess the number and sex of children in individuals with Type 1 diabetes and to determine the impact of parental diabetes on the age at onset of Type 1 diabetes," they write.

The researchers studied 697 individuals with type 1 diabetes (364 women, 333 men) who were part of a background regional German population of 350,000 people. The investigators assessed the number of children born to families, the sex of the children, and whether the family had a prior history of diabetes. They then compared those findings with 2009 government statistics for the overall region.

The investigators tallied births that took place throughout the entire lifespan, including those that occurred after the onset of diabetes.

They report that the overall fertility rate for women in the background population was 1.36 children during the reference year (2009). In the cohort of women with type 1 diabetes, however, the fertility rate fell to 0.88. In men with type 1 diabetes, the fertility rate was 0.65, the authors said.

More men with type 1 diabetes were childless compared with their female counterparts (51.1% vs 35.7%; P < .0001).

The ratio of male to female offspring was nearly equal, the researchers say. Women with diabetes gave birth to 200 girls and 199 boys (P = 1.00), whereas men with diabetes fathered 171 girls and 160 boys (P = .63). In the subgroup of children born to parents after their type 1 diabetes manifested, those sex ratios remained similar.

Maternal Diabetes May Be Protective

The authors say the presence of diabetes in fathers did not appear to have a significant effect on development of the disease in offspring, but that was not the case in mothers with diabetes.

"Although we did not find a significant influence of paternal diabetes, our data for the first time suggest that, in addition to maternal Type 2 diabetes, maternal Type 1 diabetes may also lead to a later manifestation of Type 1 diabetes."

They found that maternal type 2 diabetes delayed the onset of type 1 diabetes in children by 7.25 years on average. Maternal type 1 diabetes delayed the onset of type 1 disease in their children by 5.8 years.

"Maternal Type 1 or Type 2 diabetes increased the age at onset of Type 1 diabetes from 22.9 ± 13.7 (no maternal diabetes) to 28.6 ± 16.8 and 30.1 ± 15.1 years (p < 0.0001), respectively," the authors write.

"Therefore, irrespective of the type of diabetes, there may be a protective effect of maternal diabetes per se," they write.

They also note that dietary factors might play a role in that protective effect, as could genetic factors. They speculate that in cases of maternal type 1 diabetes, it may be that autoantibodies transferred via the placenta might provide a protective immunologic effect that helps forestall development of diabetes.

Study limitations include lack of data about socioeconomic factors, including education level and single vs partnered parents.

Several Explanations for Lower Birth Rate

The authors emphasize that decreased fecundability may not be the only reason for lower birth rates among people with type 1 diabetes. Although there have been significant improvements in maternal and fetal care in recent years, they note, pregnancies with type 1 diabetes are still associated with more complications and poorer outcomes than normal pregnancies.

"Furthermore, it can be assumed that patients recognize Type 1 diabetes as a disease with a marked genetic component and heredity," they note. "Altogether, these factors may lead to fears and concerns that result in lower birth rates in individuals with Type 1 diabetes."

The authors have disclosed no relevant financial relationships.

Diabetic Med. Published online February 23, 2012. Abstract


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