Small babies had significantly higher blood glucose and insulin levels and a higher risk of diabetes at the age of 75 and older. The risk of diabetes in old age was five-fold among those born small but who were obese in midlife compared to those with higher birth weight and low body mass index in adulthood.

- Studies have shown that small body size at birth is associated with diabetes in adulthood. However, little is known about the effect in old individuals. In our study, the association between birth weight and glucose metabolism in old age was strong in spite of the long time between the exposure and the outcome as well as the age-related changes that occur in the glucose and insulin metabolism, says Dr. Mikaela von Bonsdorff from the University of Jyväskylä.

The Finnish researcher worked with an Icelandic dataset at the National Institute on Aging, NIH, US. Iceland has one of the highest average birth weights in the world and also one of the lowest rates of diabetes. High birth weight has been attributed to the high protein nutrition and the universal use of cod oil which is known to lengthen gestation. In spite of these unique features, the present findings are in line with earlier studies conducted in the Western countries.

- In terms of identifying risk factors for diabetes, it is important to consider body size at birth along with the traditional risk factors as low birth weight seems to yield a lifetime risk for diabetes. The present findings are concerning while obesity is increasing in all age-groups, says Dr. Mikaela von Bonsdorff.

The 1682 participants belonging to the Age, Gene/Environment Susceptibility – Reykjavik (AGES-Reykjavik) Study were born between 1914 and 1935. They had taken part in the follow-up as middle aged and in old age and these data were linked with anthropometrical birth data extracted from medical records in Iceland. The international study group included researchers from the US, Iceland, the Netherlands and Finland.