RELATION OF BIRTH-WEIGHT TO MARKERS OF FETOMATERNAL BETA-CELL FUNCTION

High levels of proinsulin (PI) and of proinsulin-like molecules such a s the split product des31,32 PI (des PI) have been associated with the presence of beta-cell dysfunction, as well as with insulin resistance -associated conditions such as impaired glucose tolerance or non-insul in dependent diabetes, Since thin babies have a higher probability of developing insulin resistance in adult life, the aims of this study we re to evaluate whether birth weights would be related to the levels of intact iusulin, PI, and of des PI assayed in 111 pregnant women with normal glucose tolerance, as tested by a 100 g oral load given between the 24(th) and the 28(th) gestational week and in 48 cord-blood speci mens drawn from neonates at delivery. In the cord blood of the babies, insulin was lower (15+/-3 vs 49+/-2 pmol/l, p<0.001) and PI and des P I were higher (2.3+/-1.7 vs 0.8+/-2.1 pmol/l, p<0.001 and 1.4+/-3.3 vs 0.8+/-2.3 pmol/l, p<0.001, respectively) than in the plasma of their mothers at 24-28 weeks of pregnancy. A higher proportion of insulin pr opeptides (PI + des PI) in the serum of pregnant mothers or in the cor d blood of their neonates was associated with a significantly (p=0.01) lower weight at birth. In summary: to the extent that a high ratio of propeptides to insulin is an index of relative beta-cell dysfunction, higher PI ratios in the cord blood of smaller babies suggest that poo rer intrauterine growth is associated with reduced p-cell mass and fun ction. Thus, the present data lend support to the theory that Links re tarded intrauterine growth with adult glucose intolerance. (C) 1997, E ditrice Kurtis.