Pathways of infant and childhood growth that lead to type 2 diabetes

Although a link between small body size at birth and later type 2 diabetes has been repeatedly documented, less is known about the associations between the disease and growth during infancy. The aim of this study was to explore the pathways of infant and early growth that lead to type 2 diabetes in adult life.

We carried out a longitudinal study of 8760 subjects born in Helsinki from 1934 to 1944. On average, they had 8 measurements of height and weight between birth and 1 year of age and another 10 measurements between 1 and 12 years of age. We identified people with type 2 diabetes using a national register.

Among babies whose birth weights were 3.5 kg, slow growth in length between birth and 3 months of age predicted later disease. Rapid gain in BMI after age 2 years increased the risk of later disease in both groups of babies, but this effect was greatest among children who had slow growth in length between birth and 3 months of age. In children whose Z-scores for length decreased, an SD increase in BMI at age 12 years was associated with an odds ratio (OR) for type 2 diabetes of 1.77 (95% CI 1.50-2.09). The corresponding OR in subjects whose Z-scores for length increased was 1.42 (95% CI 1.20-1.69). Rapid gain in childhood BMI was associated with high maternal BMI and socioeconomic factors (fewer people in the home and lower social class).

Babies with above-average birth weights may develop type 2 diabetes later in life if poor living conditions lead to faltering growth in length in the first few months after birth. We speculate that growth faltering at this time is associated with lifelong impairment of insulin metabolism and inability to meet the challenge of rapid childhood increase in BMI.