[Insulin Difference of Boys and Girls at Birth]

Different opinions exist whether girls show higher insulin levels than boys at birth. Insulin values of 863 consecutively born babies whose mothers had no screening for gestational diabetes may provide clarification.

Cord serum, measured with a commercially available insulin assay, is therefore retrospectively analyzed for insulin differences in boys and girls.

Girls show higher insulin values than boys (♀6.0/♂5.2 µU/ml). Insulin-sex-difference amounts to 0.8 µU/ml [95% CI 0.3 to 1.3]; p-value 0.003. It is also found in AGA babies, in children of multiparous women, after elective caesarean section and spontaneous vaginal delivery (0.8/1.2/1.7/0.9 µU/ml; p-values 0.003/0.001/0.025/0.006). Girls of multiparous women with macrosomia (LGA/≥ 4000 g) show the highest values of insulin (13.8/13.8 µU/ml) and of insulin-sex-difference (5.5/5.6 µU/ml, p-value 0.001/0.001). This insulin difference can be seen in firstborn babies weighing less than 3640 g, but ≥ 4060 g an inverse insulin sex difference (-5.4 µU/ml; p-value 0.023) with higher insulin values in boys exists (11.3 µU/ml). Children with hyperinsulinaemia (≥20 µU/ml) (17♀, 11♂) show no insulin difference, girls weigh more than boys (154 g, p-value 0.463) and later born babies more (695 g, p-value 0.0001) than firstborns.

Higher insulin values of girls have been confirmed. An as yet unknown inverse insulin difference with higher insulin values of firstborn boys with macrosomia has been proved.