False Positive Glucose Challenge Test Research Articles

Establishing novel diagnostic criteria for the glucose tolerance test for the diagnosis of gestational diabetes and gestational hyperglycemia.

To establish diagnostic criteria for the 75-g 2-h glucose tolerance test (GTT) to diagnose gestational diabetes and define the clinical entity of gestational hyperglycemia. A retrospective analysis was performed of the results from 500 patients who had a 75-g 1-h glucose challenge test (GCT) in early pregnancy as part of a two-step approach to screening and testing for gestational diabetes. The selected cohort was considered to have normal islet β-cell function, and upper glycemic levels of normal glucose tolerance in the third trimester were statistically calculated, taking the cutoff threshold values to be the diagnostic criteria for the 75-g 2-h GTT. Gestational hyperglycemia was diagnosed from the false-positive GCT result when ≥8.0 mmol/L (144 mg/dL). The diagnostic criteria for the 75-g 2-h GTT were calculated as follows: fasting plasma glucose ≥5.4 mmol/L (97 mg/dL); 1-h plasma glucose ≥10.5 mmol/L (189 mg/dL); and 2-h plasma glucose ≥8.4 mmol/L (151 mg/dL). The new criteria confirmed a prevalence of gestational diabetes of 11.1% and gestational hyperglycemia of 13.6% in the study population. Novel diagnostic criteria for the 75-g 2-h GTT were established by statistical analysis. This resulted in a more acceptable prevalence of gestational diabetes in our community and the false-positive GCT allowed the detection of gestational hyperglycemia.

Incidence of large for gestational age and predictive values of third-trimester ultrasound among pregnant women with false-positive glucose challenge test

This cohort study aimed to determine the association between false-positive 50-g GCT and incidence of LGA and to evaluate predictive roles of third-trimester ultrasonographic examination. A total of 200 women with false-positive 50-g GCT and 188 women without GDM risks were enrolled. Third-trimester ultrasonographic examinations were offered. Rate of LGA during third trimester and at birth were compared between groups. Factors associated with LGA and diagnostic properties of third-trimester ultrasonography were evaluated. Incidence of LGA by third-trimester ultrasound and at birth were significantly higher in women with false-positive GCT (19.0% vs. 10.6%, p = .03 and 22% vs. 13.8%; p = .04). Factors associated with LGA included multiparity (adjusted OR 2.32, p = .01), excessive weight gain (adjusted OR 2.57, p = .01) and LGA by ultrasound (adjusted OR 9.79, p < .001). Third-trimester ultrasonography had 47.1% sensitivity, 92.1% specificity and LR + and LR- of 5.96 and 0.57 in identifying LGA infants. Impact statement What is already known on this subject? Women with abnormal GCT but normal OGTT (false positive GCT) might have some degree of glucose intolerance so that GDM-related outcomes could develop, including LGA, macrosomia, shoulder dystocia, and caesarean delivery. Roles of ultrasonography in the prediction of LGA and macrosomia has been reported with mixed results. What do the results of this study add? The results showed that the incidence of LGA, by third-trimester ultrasound and at birth, were significantly increased in women with false-positive GCT. Multiparity, excessive weight gain and LGA by third-trimester ultrasound significantly increased the risk of LGA. Third-trimester ultrasonography had 47.1% sensitivity, 92.1% specificity and LR + and LR- of 5.96 and 0.57 in identifying LGA infants. What are the implications of these findings for clinical practice and/or further research? More intensive behavioural and dietary interventions, together with weight gain control and monitoring, may be needed in women with false-positive GCT to minimise the risk of LGA. Third trimester ultrasonographic examination might be helpful to detect and predict LGA at birth and should be included into routine clinical practice. Further studies that are more widely generalisable are needed to elucidate the relationship between false-positive GCT and adverse pregnancy outcomes and to investigate the benefits of ultrasonographic examination in the prediction of LGA and macrosomia.

Association between false positive glucose challenge test results and large-for-gestational-age infants: a retrospective cohort study

ObjectivesThere is no consensus regarding a possible relation between false positive glucose challenge test (GCT) results and large-for-gestational-age (LGA) infants. This study aimed to clarify the association between false positive...

Relationship between 50-g glucose challenge test and large for gestational age infants among pregnant women without gestational diabetes

The study aimed to compare the incidence of large for gestational age (LGA) infants between women with a false positive and normal glucose challenge test (GCT), and to evaluate the factors associated with LGA. A total of 480 pregnant women at risk for gestational diabetes mellitus (GDM); 160 with a false positive GCT and 320 with normal GCT results were included. The incidence of LGA and other pregnancy outcomes were compared between the two groups. Possible associated factors for LGA were also evaluated. Women with a false positive GCT were significantly older and more likely to be multiparous. The incidence of LGA was comparable between the false positive and normal GCT groups (15.6% vs. 13.1%, p = .456). Other pregnancy outcomes were also comparable. Logistic regression analysis showed that pre-pregnancy underweight significantly reduced the risk of LGA (adjusted OR 0.25, 95% CI 0.07–0.87, p = .029) while a second trimester weight gain >7 kg significantly increased the risk of LGA (adjusted OR 3.13, 95% CI 1.67–5.89, p < .001).Impact StatementWhat is already known on this subject? Women with a false-positive GCT (abnormal GCT but normal OGTT) can be considered as having an early form of glucose intolerance which similar adverse outcomes to GDM could develop. Previous studies have reported that a mild maternal hyperglycaemia in the absence of GDM is associated with LGA, macrosomia, shoulder dystocia and a caesarean delivery. There is no current recommendation for any intervention or treatment among women with a false positive GCT.What the results of this study add? The results of this study showed that an incidence of LGA was not significantly increased in the false positive GCT groups and that other pregnancy outcomes were comparable. A pre-pregnancy underweight significantly reduced the risk of LGA while a second trimester weight gain >7 kg significantly increased the risk of LGA.What the implications are of these findings for clinical practice and/or further research? As a gestational weight gain is modifiable, behavioural and a dietary intervention as well as a close monitoring of the weight gain could help in lowering the risk of LGA, even in the absence of GDM. Further studies which are more widely generalisable are needed to elucidate the relationship between 50 g GCT and the adverse outcomes and to investigate the benefits of a specific intervention among this specific group of women.

Clinical significance of a false positive glucose challenge test in patients with a high body mass index.

To determine if there is an increased maternal or neonatal morbidity in overweight and obese patients with a false positive glucose challenge test (GCT). Patients with a body mass index (BMI) ≥25.0 at registration were included in this prospective 36-month study. The study cohort consisted of patients with a false positive (FP) GCT, with two comparison cohorts: those with a (1) screen negative (SN) GCT result and (2) true positive (TP) GCT result. Risks were reported as odd ratios with 95% confidence intervals, with a P<0.05 considered as significant. There were 60 patients in the FP cohort, 106 in the SN cohort, and 64 in the TP cohort. When the BMI of the FP cohort was compared with either the SN cohort or TP cohort, differences were non-significant (SN 32.3 vs. FP 33.3 kg/m2, P=0.067) and (FP 33.3 vs. TP 34.4 kg/m2, P=0.303). When comparing the FP cohort to the SN cohort, patients in the FP group had significantly more gestational hypertension and pre-eclampsia. There was a trend towards delivering large for gestational weight infants and an infant ≥4000 g in the FP cohort, but this fell short of reaching statistical significance. When comparing the FP to TP cohorts, rates of gestational hypertension, pre-eclampsia, and infants ≥4000 g were similar; however, neonatal morbidity was increased in the TP group. Overweight and obese patients with a FP glucose challenge screen are more likely to have adverse maternal outcomes. Neonatal morbidity was not increased.

The impact of gestational weight gain in different trimesters of pregnancy on glucose challenge test and gestational diabetes

PurposeAssessing the effects of excessive weight gain before pregnancy, in the first and second trimesters and in the month preceding glucose challenge test (GCT) on GCT results and gestational diabetes...

268: Screening for gestational diabetes: does a false positive glucose challenge test predict adverse pregnancy outcome?

268: Screening for gestational diabetes: does a false positive glucose challenge test predict adverse pregnancy outcome?

Filling the Gaps through Partnerships, Collaboration, and Flexible Funding

### Purpose Assessing the effects of excessive weight gain before pregnancy, in the first and second trimesters and in the month preceding glucose challenge test (GCT) on GCT results and gestational diabetes mellitus (GDM). ### Study design This prospective cohort study evaluated 1279 pregnant women who were referred for their first prenatal visit in 2012--2015. Mother9s body mass index (BMI) was recorded before pregnancy, during the first visit and every 4 weeks until 28 gestational weeks. All mothers underwent GCT at 28 weeks and when 1 h glucose ≥140 mg/dL (≥7.8 mmol/L), they were referred for a 100 g fasting glucose 3 h glucose tolerance test. ### Results Obesity and being overweight prior to pregnancy were associated with 2.8-fold and 1.5-fold higher rates of developing GDM (p\<0.001, p=0.04) and 1.9-fold and 1.8-fold higher rates of having false-positive GCT results (p\<0.001). First-trimester excessive weight gain was significantly associated with false-positive GCT in women who were lean, overweight and obese before pregnancy (all p\<0.001). When these women kept gaining excessive weight during the subsequent period the risk of developing GDM was significantly increased regardless of their pre-pregnancy BMI (p=0.03). When these women adhered to the recommended weight gain during the subsequent period, the risk of developing GDM was not increased, however the risk of having false-positive GCT remained high (p\<0.001). ### Conclusions Elevated pre-pregnancy BMI independently increases the risk of GDM and false-positive GCT. First trimester weight gain is the most important predictor of GCT and GDM regardless of pre-pregnancy BMI. The weight gain during the subsequent period affects the risk of developing GDM only in women with excessive first-trimester weight gain.

Obstetric outcomes with a false-positive one-hour glucose challenge test by the Carpenter-Coustan criteria

Objective. Pregnancies complicated by a false-positive one-hour glucose challenge test (GCT), as determined by the National Diabetes Data Group (NDDG) criteria, have higher rates of adverse maternal and neonatal outcomes. This study was conducted to determine if pregnancies complicated by a false-positive GCT, as determined by the Carpenter-Coustan (CC) criteria, also have higher rates of adverse maternal and neonatal outcomes.Study design. In this retrospective case-control study, we compared 165 patients with a false-positive GCT, as determined by the Carpenter-Coustan criteria, to a cohort of 165 pregnant controls with a normal screening GCT. Multiple variables for maternal and neonatal outcomes were compared between the two groups.Results. The racial distribution and gestational age of delivery were similar in both groups. The study group had a higher one-hour GCT (148.2 mg/dl vs. 95.3 mg/dl, p < 0.001), was older (27.4 yrs vs. 23.8 years, p < 0.001), was more likely to be multiparous (71.5% vs. 58.2%, p = 0.011), and had a higher BMI (26.7 kg/m2 vs. 24.6 kg/m2, p = 0.002). There were no differences between the two groups in mode of delivery, birth weight, rates of macrosomia, shoulder dystocia, antenatal death and maternal laceration. There were also no differences between the two groups in rates of preeclampsia, chorioamnionitis, endometritis, ICN admission, neonatal hypoglycemia, Erb's palsy, clavicular fracture, neonatal sepsis, neonatal death or use of phototherapy.Conclusion. Women with a false-positive one-hour GCT by the Carpenter-Coustan criteria do not have higher rates of adverse perinatal outcomes. Using the Carpenter-Coustan criteria to diagnose GDM appears to be superior to NDDG criteria in terms of avoiding adverse maternal and neonatal outcomes.

Elevated serum levels of visfatin in gestational diabetes: a comparative study across various degrees of glucose tolerance

Concentrations of visfatin are increased in insulin-resistant conditions, but the relationship between visfatin and insulin and/or insulin resistance indices in pregnancy remains unclear. Insulin resistance in pregnancy is further accentuated in women with gestational diabetes mellitus (GDM). Thus we assessed serum levels of visfatin in pregnant women with varying degrees of glucose tolerance. Fasting visfatin levels were measured at 28 weeks of gestation in 51 women divided according to their response to a 50-g glucose challenge test (GCT) and a 75-g OGTT: control subjects (n = 20) had normal responses to both a GCT and an OGTT; the intermediate group (IG; n = 15) had a false-positive GCT, but a normal OGTT; the GDM group (n = 16) had abnormal GCTs and OGTTs. There were no age or BMI differences between analysed groups. Across the subgroups there was a progressive increase in glucose and insulin at 120 min of the OGTT (p < 0.01). This was accompanied by an increase in visfatin, from 76.8 +/- 14.1 ng/ml in the control subjects, to 84.0 +/- 14.7 ng/ml in the IG group and 93.1 +/- 12.3 ng/ml in the GDM group (p < 0.01 for GDM vs control subjects). There was a positive correlation between visfatin and fasting insulin (r = 0.38, p = 0.007) and insulin at 120 min of the OGTT (r = 0.39, p = 0.006). An increase in fasting visfatin, the levels of which correlate with both fasting and post-glucose-load insulin concentrations, accompanies worsening glucose tolerance in the third trimester of pregnancy. However, the significance of these findings, and in particular the role of visfatin in the regulation of insulin sensitivity during pregnancy, remains to be elucidated.

Adiponectin and glucose levels in women with negative or false positive glucose challenge test

Objective To determine whether there is a correlation between adiponectin levels and glucose levels in women screened for gestational diabetes mellitus by means of a 50-g oral glucose challenge test, and to examine the difference in adiponectin levels between women who tested negative, and those who tested false positive. We further calculated the correlations between adiponectin levels and glucose levels, body mass index, gestational age and maternal age. Methods A case control study included 171 mothers with negative or false positive results in the 1-h 50-g glucose challenge test at 24–28 gestational weeks. Serum adiponectin levels were determined by radioimmunoassay at the time of the glucose challenge test. Results There was a significant difference between women who tested negative at screening, and those who tested false positive with respect to age, prepregnancy body weight and body mass index, and adiponectin levels. Correlation analysis showed adiponectin levels to be negatively correlated to glucose levels ( r = −0.193, P = 0.011). To examine the association between glucose levels, adiponectin levels and demographic variables, multiple linear regression analysis was carried out. Prepregnancy body mass index and age accounted for 14.6% of the variance in the glucose challenge test. Adiponectin levels did not contribute independently to the variation in glucose levels. A further multiple linear regression analysis was undertaken to investigate the association between adiponectin levels and age, prepregnancy body mass index and glucose levels in the glucose challenge test. In this regression model, prepregnancy body mass index and age explained 12.1% of the variance in adiponectin levels. Conclusions In conclusion, our study indicated a negative correlation between adiponectin and glucose levels in women screened for gestational diabetes mellitus by a glucose challenge test. We further found that maternal age and body mass index were independent risk factors for a false positive glucose challenge test. Reduced adiponectin levels in women who tested false positive on the glucose challenge test were dependent on advanced age and higher body mass index.

Adverse effects of screening for gestational diabetes: a prospective cohort study in Toronto, Canada.

To investigate the adverse effects associated with a false positive 50 g glucose challenge test for gestational diabetes mellitus (GDM). Consecutive women attending a prenatal registration clinic at a large community hospital in suburban Toronto, Canada. Prospective cohort study of women between 12 and 24 weeks' gestation with no previous history of diabetes mellitus or GDM. Main outcome measures included anxiety (Spielberger's State-Trait Anxiety Inventory), depression (Centers for Epidemiologic Studies Depression Scale), perceived maternal health, and concern about health of the newborn. Among 2564 eligible subjects, there were 897 subjects with complete data at enrollment and at 32 weeks' gestation, including 88 who had false positive glucose challenge test results. At 32 weeks, only 20% (95% confidence limits 11%, 28%) of women with false positive glucose challenge test results rated their health as excellent, compared with 38% (35%, 42%) of those having negative results and those not tested (P = 0.001). These results were sustained at 36 weeks. There was no association between glucose challenge test result and the change in anxiety (P = 0.57), depression (P = 0.09) or concern about health of the newborn (P = 0.91) between baseline and 32 weeks' gestation, nor were these associations found at 36 weeks. False positive glucose challenge test results are about six times more likely than true positive results in the general population. Pregnant women with false positive GDM screening results experience a significant decline in their perception of their own health. These adverse effects should be taken into account when deciding about a policy of screening all pregnant women for gestational diabetes.