[Early diagnosis of gestational diabetes by amniotic fluid insulin levels?]

Gestational diabetes mellitus (GDM) occurs in 3-5% of all pregnant women. As there is no general screening in Germany, many cases remain undetected. Maternal as well as foetal morbidity are increased in GDM. The aim of this study was to investigate whether amniotic fluid insulin or C-peptide levels, collected by genetic amniocentesis in early pregnancy, are predictive for gestational diabetes. Patients at risk for developing GDM might be identified and treated very early.

260 patients having a genetic amniocentesis were included in this prospective trial. Insulin and C-peptide levels were identified in frozen amniotic fluid samples. All patients should undergo an oral glucose tolerance (oGTT) test at 24-28 weeks of gestation. Only cases with normal genetic screening, normal foetal sonomorphology and birth at term were included in this trial. 90 of 260 patients having an amniocentesis underwent the oGTT and fulfilled all inclusion criteria.

GDM was diagnosed in 8 patients, in another 6 patients only one glucose level was out of the normal range. Neither amniotic fluid insulin nor C-peptide levels showed significant differences between normal and GDM pregnancies. The insulin and C-peptide levels did not correlate with blood glucose levels or with foetal weight.

In contrast to literature reports, according to these data no relationship between amniotic fluid insulin or C-peptide levels and gestational diabetes can be assumed. Amniotic fluid insulin or C-peptide levels are not predictive for GDM.