Can glucose tolerance test predict fetal hyperinsulinism?
OBJECTIVE
To establish cut off levels for oral glucose tolerance test in pregnancy using fetal hyperinsulinism as a clinical endpoint.


METHODS
Capillary blood glucose levels at 0, 1, and 2 hours after the ingestion of either 1 g/kg or 75 g glucose, at 28 (SD 5) weeks of gestation were analysed in 220 women with elevated amniotic fluid insulin levels [> or =42 pmol/L (> or =7 microU/mL)] after a mean (SD) of 31 weeks (3) and in 220 nondiabetic controls.


RESULTS
In women with elevated amniotic fluid insulin levels the mean (SD) capillary blood glucose values at 0, 1, and 2 hours were 5.2 mmol/L (1.0) [94 mg/dL (18)], 10.5 mmol/L (1.4) [189 mg/dL (25)] and 8.2 mmol/L (2.0) [147 mg/dL (36)], respectively. The one-hour value had the highest sensitivity to predict elevated amniotic fluid insulin levels. The 5th centile of the one-hour blood glucose levels representing a detection rate of 95% was 8.9 mmol/L (160 mg/dL).


CONCLUSIONS
Glucose cut off levels in most established oral glucose tolerance test criteria are too high, to accurately predict amniotic fluid hyperinsulinism. A one-hour test may be sufficient for detecting amniotic fluid hyperinsulinism. Since different loads (1 g/kg, 75 g or 100 g) and blood fractions (venous plasma or capillary blood) have minimal impact on oral glucose tolerance test results, a single one-hour cut off of 8.9 mmol/L (160 mg/dL), independent of the sampling method, may be appropriate for the diagnosis of gestational diabetes mellitus severe enough to cause amniotic fluid hyperinsulinism.
Weiss
P A
PA
Department of Obstetrics and Gynaecology, University of Graz, Austria.
Haeusler
M
M
Tamussino
K
K
Haas
J
J
D000328:Adult; D000653:Amniotic Fluid / Q000737:chemistry; D001786:Blood Glucose / Q000378:metabolism; D016640:Diabetes, Gestational / Q000175:diagnosis*; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis* / Q000209:etiology; D005947:Glucose / Q000008:administration & dosage; D005951:Glucose Tolerance Test / Q000379:methods / Q000592:standards*; D006801:Humans; D006946:Hyperinsulinism / Q000175:diagnosis* / Q000209:etiology; D007328:Insulin / Q000378:metabolism; D011247:Pregnancy; D012680:Sensitivity and Specificity
D001786:Blood Glucose; D007328:Insulin; D005947:Glucose