Die Messung des Nüchternblutzuckers als Screeningmethode für Gestationsdiabetes - Voraussetzungen für eine erfolgreiche Durchführung

Abstract

Purpose: In 1999 we could demonstrate that fasting plasma glucose is a useful new screening test for gestational diabetes (Perucchini et al., 1999). In this study we wanted to evaluate the effectiveness of this method in clinical practice. Patients and Methods: 637 pregnant women who had attended antenatal clinics at the University Hospital in Zurich between 2000 and 2003, and had been screened for gestational diabetes with fasting plasma glucose after 24 weeks of gestation were included. The retrospectively obtained results were analyzed by descriptive statistical methods. A cut-off value of ≥4.8 mmol/l as proposed by Perucchini et al. was used to prescribe an oral glucose tolerance test. Results: 179 patients had a fasting plasma glucose of ≥4.8 mmol/l, of which 141 cases could be analyzed. We could reproduce our earlier results to a large degree: the rate of oral glucose tolerance test was 28.1% (1st study 30.0%), the positive predictive value was 20.6% (1st study 25.4%), with a difference in prevalence of 4.6% (low risk population) to 10.2% (1st study, high risk population). However, we also found that a substantial number of the patients who had elevated screening fasting plasma glucose levels had normal results in the oral glucose tolerance test (false positive rate 79.4%, 1st study 22%). Conclusion: Fasting plasma glucose at a cut-off value of ≥4.8 mmol/l offers an alternative method to screen for gestational diabetes with good implementation in clinical practice. The lower fasting plasma glucose levels in the oral glucose tolerance test in a substantial part of the pregnant women seems to indicate that a lot of patients, despite having been instructed orally, had not fasted before the screening test. Thus providing detailed oral and written instructions to the patients is mandatory to obtain valid results.