Background and aims Given the heritability of a diabetic predisposition and the need for a timely initiation of screening and preventive measures it seems prudent to identify infants from (a) a mother with preexisting diabetes mellitus (DM) or (b) with gestational diabetes (GDM), in contrast to infants with simple macrosomia (M).

Methods Identification of pregnant women with DM, GDM or fetal macrosomia in a level III obstetric department over a period of 5 months, using fetal ultrasound, medical history, oral glucose tolerance test and further variables. Collection of anthropometric and metabolic data from mother and infant. Measurement of fructosamine, IGF, insulin, leptin and retinol binding-protein 4 from cord blood.

Results Mother-infant dyads with GDM (n = 64), M (n = 18), DM (4) and control infants (C) (n = 47) were studied. Preconceptional weight, weight at delivery and BMI were significantly different between mothers with GDM and M infants versus C infants, respectively. Infants’ anthropometric and blood glucose profile data were different from C infants in GDM and M group, but only anthropometric data were different between GDM and M infants. None of the 5 metabolic variables in cord blood was different between GDM and C group, but leptin and IGF were lower in GDM vs. M and higher in M vs. controls (p < 0.001).

Conclusions With the current screening tests cases of GDM may have been undetected in the M group. With adherence to screening guidelines and a high compliance of pregnant GDM women with medical recommendations metabolic differences between GDM and C infants might vanish and be restricted to anthropometric variables.