Children of parents with any type of diabetes appear to be more likely to develop type 1 diabetes, as are children born to overweight or obese mothers when neither parent has diabetes, researchers in Sweden reported in Diabetologia.

“Over recent years, the incidence of type 1 diabetes has been increasing worldwide, including in Sweden. The reason for such an increase is not fully understood, but there is clear evidence that environmental factors are involved in the etiology of the disease in genetically susceptible individuals,” they wrote.

One potential risk factor that is being explored is high maternal BMI.

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In this study, the researchers sought to assess the relationship between maternal overweight or obesity and the risk for type 1 diabetes in offspring of parents with and without diabetes, and of different ethnicities. They followed 1,263,358 children born between 1992 and 2004 in Sweden and followed them until diagnosis of type 1 diabetes, emigration, death or the study’s conclusion in 2009.

During the study period, 5,771 children were diagnosed with type 1 diabetes. Of these children, 5,155 had parents who were both born in Nordic countries, including Sweden, Norway, Finland, Denmark and Iceland; 322 had parents who were both born outside Nordic countries; and 294 had one parent born in a Nordic country and another born outside.

Results revealed an increased risk for type 1 diabetes among children of parents with any type of diabetes, regardless of parental ethnicity. In Nordic families, for whom the data were most robust, the risk for type 1 diabetes was increased five-fold for children who had a father with any type of diabetes.

High first trimester maternal BMI was linked to a 33% increased risk for type 1 diabetes only in children born to parents without diabetes, as compared with maternal BMI in the normal range, defined as 18.5 to 25 (incidence rate ratio [IRR]=1.33; 95% CI, 1.20-1.48), according to the data.

“The finding that first trimester maternal obesity was a risk factor for type 1 diabetes only in offspring of parents without diabetes, and that maternal obesity caused no ‘extra’ risk in offspring of parents with diabetes, clearly suggest that heredity for type 1 diabetes is the strongest risk factor for the two for development of type 1 diabetes in the next generation,” the researchers wrote.

“This population-based study from Sweden demonstrates significantly increased risks of type 1 diabetes in offspring of both mothers and fathers with diabetes and regardless of parental migration background. The highest risks were noted in offspring of mothers and fathers with type 1 diabetes,” they concluded.

“Furthermore, maternal overweight and obesity in early pregnancy was associated with increased risk of type 1 diabetes in the offspring of parents without diabetes. Therefore prevention of overweight and obesity in women of reproductive age — currently increasing in all countries — may contribute to a decreased incidence of type 1 diabetes.”


  1. Hussen HI, Persson M, Moradi T. Diabetologia. 2015;doi:10.1007/s00125-015-3580-1.