“We found a 20 per cent increase in risk for every extra kilogram gained, but the risk of developing type 1 diabetes is already relatively low,” says Lars Christian Stene one of the main authors of the study.
The Norwegian and Danish researchers studied weight gain in nearly 100 000 children in the Norwegian Mother and Child Cohort Study and the Danish National Birth Cohort study.
Approximately half a per cent of children develop type 1 diabetes during childhood. Although the number is quite low, type 1 diabetes is nevertheless one of the most common chronic diseases among children.
Researchers know that genes play an important role in the development of the disease, but they know less about which environmental factors are important.
“The relationship between weight gain and type 1 diabetes is mainly important for the research community in order to understand the possible risk factors for type 1 diabetes”, says Stene.
High weight gain is a risk factor
It is important that children gain weight their first year. This study found that children put on an average of 6 kg in the first year, with some variation.
“We must remember that there are many children who gain more than 6 kg in the first year, but the majority will not develop type 1 diabetes. There is therefore no reason for mothers or public health nurses to worry, or to change their infant nursing practices”, says Stene.
The study also examined children's length, but found no association between the change in length during the first year of life and type 1 diabetes.
Important contribution to research
Although it is too early to give any health advice, the study provides an important contribution to diabetes research because it is the first study that has followed a large group of children from the general population over so many years (up to 13 years).
The study provides solid evidence that there is an association between weight gain and type 1 diabetes, and therefore supports the role of environmental factors on the development of type 1 diabetes.
It is unclear why weight gain is associated with type 1 diabetes. It may have to do with insulin secretion and insulin sensitivity, in that weight gain increases the need for insulin to such an extent that the cells that produce insulin may be stressed and become more susceptible to insults:
“A possible explanation for this association could be that higher weight gain increases the pressure on beta cells to produce insulin, in addition to an altered intestinal flora or inflammation that is often seen in obesity”, explains Maria Magnus, who is first author of the article.
About the study
The study included over 99,000 children in the Norwegian Mother and Child Cohort Study (MoBa) and the Danish National Birth Cohort (DNBC). Information on birth weight and length were obtained from birth records, while information on weight and length at 12 months was obtained from mothers through questionnaires. Information about the diagnosis of type 1 diabetes was available from national childhood diabetes registries.
The results were controlled for a number of factors, such as gender, birth weight and length, and various information about the child's mother and father.
The results are presented in the prestigious journal JAMA Pediatrics.
The study was conducted by the NIPH in collaboration with the University of Oslo, University of Bergen, Oslo University Hospital, Haukeland University Hospital, Østfold Hospital, Statens Serum Institut Denmark and Copenhagen University Hospital, Herlev, Denmark.
Maria C. Magnus; Sjurdur F. Olsen; Charlotta Granström; Geir Joner; Torild Skrivarhaug; Jannet Svensson; Jesper Johannesen; Pål Njølstad; Per Magnus; Ketil Størdal; Lars C. Stene (2015) Infant Growth and Risk of Childhood-Onset Type 1 Diabetes in Children From 2 Scandinavian Birth Cohorts. JAMA Pediatr. 2015;169(12):e153759