A new study from university researchers in the United States has found an association between low birth weight and the risk of developing type 2 diabetes later in life.
The research, led by Dr. Tiange Wang and Dr. Lui Qi of the Tulane University School of Public health and Tropical Medicine, shows that a genetically lowered birth weight increases the risk of developing type 2 diabetes.
While low birth weight has been associated with a high risk of type 2 diabetes in observational studies, it remains unclear whether this relation is causal. Factors due to socioeconomic status and lifestyle are difficult to fully eliminate in observational studies.
However, genetic association analysis is less likely affected by these confounding factors and has been increasingly employed to establish causality. This is the first study to look at the genetic link.
This new study included 3,627 type 2 diabetes cases and 12,974 controls of European ancestry from the Nurses’ Health Study, a large study of nurses in the US, and the Health Professionals Follow-up Study, a large study of male health professionals in the US. The authors created a genetic risk score (GRS) based on five low birth weight related genetic variations known as single nucleotide polymorphisms (SNPs).
The analysis showed that for each one point increase in GRS, with the score ranging from one to 10, the risk of developing type 2 diabetes increased by 6%. Using a statistical technique called Mendelian randomisation, the authors further found evidence that the low birthweight was actually causing the excess risk in type 2 diabetes.
This type of analysis is, say the authors, a new approach for establishing causal relationships in studies of this nature.
‘Evidence from both population and experimental studies has suggested that restricted early life development has long-term structural and functional influence on individuals’ predisposition to an increased risk of metabolic diseases such as type 2 diabetes,’ the study report says.
‘However, to our knowledge, this study is the first to investigate the potential causal relation between low birth weight and risk of type 2 diabetes,’ it adds.
It also explains that since low birth weight represents restricted intrauterine growth, or foetal growth, it cannot be ruled out that it is in fact the risk factors for this restricted growth that are causing the low birthweight and in turn causing type 2 diabetes to develop. Risk factors for restricted intrauterine growth include malnutrition, anaemia, infections, and placental insufficiency.
‘A genetically lowered birth weight was associated with increased susceptibility to type 2 diabetes. Our findings support a potential causal relation between birth weight and risk of type 2 diabetes, providing novel evidence to support the role of intrauterine exposures in the pathogenesis of type 2 diabetes,’ the study concludes.
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