No association between birth weight and Type 1 diabetes mellitus - a twin-control study

Aims To Investigate, by means of a twin-control study, whether there is a r elationship between birth weight and Type 1 diabetes mellitus. Methods In the youngest part (n = 20 888 pairs) of the Danish Twin Register , 95 twin pairs (26 monozygotic and 69 dizygotic) with Type 1 diabetes were identified. Information about birth weight and birth length, prematurity, maternal age and parity was obtained from midwives' records and from the Da nish Medical Birth Registry and analysed using Student's two-sided t-test, Chi-square test and logistic regression. Results Birth data were available for 83 diabetic and 51 healthy twin indiv iduals, altogether 67 twin pairs (20 monozygotic and 47 dizygotic). Mean bi rth weight was 2537 g and 2565 g (NS) in monozygotic and dizygotic pairs an d the corresponding length at birth 47.6 cm and 48.2 cm (NS). In pairs disc ordant for diabetes, the mean birth weight was 2538 g in twins with diabete s and 2549 g in twins without diabetes (NS). Logistic regression in discord ant pairs showed no relationship between diabetes status and birth weight, birth length, birth order, sex or prematurity. Logistic regression in conco rdant vs. discordant pairs showed no effect of mean birth weight and birth length, maternal age, parity or weeks of prematurity. Conclusions There is no association between Type 1 diabetes mellitus and bi rth weight in this study. Furthermore, variables related to birth weight: a nd length cannot explain why some pairs are concordant while other remain d iscordant.