Perinatal risk factors for diabetes in later life

Low birth weight is consistently associated with an increased risk of type 2 diabetes in adulthood, but the individual contributions from poor fetal growth and preterm birth are not known. We therefore investigated the significance of these two factors separately.

We identified a cohort of subjects born preterm or with low birth weight at term at four major delivery units in Sweden from 1925 through 1949. A comparison cohort of subjects was identified from the same source population. Of 6,425 subjects in all, 2,931 were born at <37 weeks of gestation and 2,176 had a birth weight <2,500 g. Disease occurrence among participants was assessed through nationwide hospital registers from 1987 through 2006.

During follow-up, there were 508 cases of diabetes. Low birth weight was strongly negatively associated with risk of diabetes (P for trend <0.0001). Both short gestational duration and poor fetal growth were associated with later diabetes (P for trend <0.0001 and <0.0004, respectively). Very preterm birth (< or =32 weeks of gestation at birth) was associated with a hazard ratio (HR) of 1.67 (95% CI 1.33-2.11) compared with term birth. Birth weights below 2 SDs of mean birth weight for gestational age were associated with an HR of 1.76 (1.30-2.38) compared with birth weights between the mean weight and the weight at 1 SD above the mean.

Our results suggest that the association between low birth weight and diabetes is due to factors associated with both poor fetal growth and short gestational age.