Screening for gestational diabetes: one-hour carbohydrate tolerance test performed by a virtually tasteless polymer of glucose

A Simple Index for Detection of Gestational Diabetes Mellitus

The conventional screening test for gestational diabetes mellitus is measurement of plasma glucose 1 hour after 50 g glucose by mouth. The sensitivity and specificity of this test are lower than desirable; we therefore developed an index including other plasma constituents. In a preliminary study, 138 pregnant women had the standard oral glucose load screening test, and plasma fructosamine and total proteins were measured, in addition to glucose, in the 1-hour samples. An index value (I) was calculated as [fructosamine (μmol/L)÷total proteins (g/L)]×[glucose (mmol/L)÷100]. Cut-off values for I were then assessed in a second prospective study, of 642 pregnant women. Definitive diagnosis of gestational diabetes was by oral glucose tolerance test (OGTT). The index was also assessed in terms of fetal macrosomia (birthweight ≥ 4000 g).

With a cut-off value of I=27.2, sensitivity was 98%, specificity 89%, diagnostic efficiency 90%, positive likelihood ratio 8.76. Application of the index would have avoided 42% of the OGTTs demanded by the standard screening test, reducing false positives from about 24% to 10%. Predictive efficacy for macrosomia was 10.3% versus 7.9%.

Our index offers an efficient screening test for gestational diabetes, and with more stringent cut-off points may be applicable as a single-step diagnostic procedure.

Sensitivity and specificity of ultrasonography as a screening tool for gestational diabetes mellitus

OBJECTIVE

To evaluate diagnostic accuracy and efficiency of ultrasound markers of gestational diabetes (GDM) and propose an ultrasound based scoring system suitable for screening (UGDS).

METHODS

110 women with singleton pregnancies and established maternal and/or pregnancy related risk factors for GDM were scanned at/or after 24 weeks gestation followed by administration of a 3 hour 100-gram oral glucose tolerance test (oGTT). A number of ultrasound markers were determined/measured, including fetal adipose subcutaneous tissue, asymmetrical macrosomy, cardiac circumference, cardiac width, and interventricular septum thickness, immature appearance of placenta, intensified breathing movements, polyhydramnios and placental thickness. Each ultrasound GDM marker was assigned one point to create the ultrasound gestational diabetes screening score (UGDS).

RESULTS

All ultrasound GDM markers were positively correlated to the disease P < 0.0001. The strongest independent predictor of GDM was an immature appearance of placenta (RR 40.1 95% CI 5.9-271.0, P < 0.0001). Receiver operator characteristics (ROC) showed an area under the curve of 95.7% confirming good ability of UGDS to discriminate between positive and negative oGTT. We propose a UGDS score of 4 providing sensitivity of 90.9%, and specificity 89.6%.

CONCLUSIONS

This study suggests that UGDS is a good predictor of GDM.

A simple index for detection of gestational diabetes mellitus

The conventional screening test for gestational diabetes mellitus is measurement of plasma glucose 1 hour after 50 g glucose by mouth. The sensitivity and specificity of this test are lower than desirable; we therefore developed an index including other plasma constituents. In a preliminary study, 138 pregnant women had the standard oral glucose load screening test, and plasma fructosamine and total proteins were measured, in addition to glucose, in the 1-hour samples. An index value (I) was calculated as [fructosamine (micro mol/L) divided by total proteins (g/L)]x[glucose (mmol/L) divided by 100]. Cut-off values for I were then assessed in a second prospective study, of 642 pregnant women. Definitive diagnosis of gestational diabetes was by oral glucose tolerance test (OGTT). The index was also assessed in terms of fetal macrosomia (birthweight>or=4000 g). With a cut-off value of I=27.2, sensitivity was 98%, specificity 89%, diagnostic efficiency 90%, positive likelihood ratio 8.76. Application of the index would have avoided 42% of the OGTTs demanded by the standard screening test, reducing false positives from about 24% to 10%. Predictive efficacy for macrosomia was 10.3% versus 7.9%. Our index offers an efficient screening test for gestational diabetes, and with more stringent cut-off points may be applicable as a single-step diagnostic procedure.

To screen or not to screen for gestational diabetes mellitus. The clinical quagmire

Although there continues to be a lack of agreement about the most appropriate way to screen for GDM, screening remains the standard of care in this country. Universal screening of all pregnant women maximizes sensitivity but has significant financial implications because of its increased costs. Additional studies are needed that apply cost-analysis to various screening protocols to identify cost-effective screening strategies.

Screening and testing for gestational diabetes mellitus

Gestational diabetes mellitus is defined as carbohydrate intolerance of variable severity first diagnosed during pregnancy. Although universal screening for gestational diabetes mellitus is practiced by more than 75% of obstetricians in the United States, agreement is lacking worldwide regarding the appropriateness of this approach. This article discusses the assumption that some type of screening program is desirable and considers how best to conduct screening and diagnostic testing for gestational diabetes mellitus.

Screening and diagnosis of gestational diabetes

This chapter discusses the evidence for the existence of an entity called 'gestational diabetes', suggesting that it can be understood in terms of risk to the pregnancy and/or risk to the mother. Various diagnostic criteria used in various parts of the world are described, and a rationale for using pregnancy-specific criteria is put forth. Universal screening approaches are also characterized. Barriers to the universal adoption of a single screening scheme and set of diagnostic criteria are outlined.

Diagnosis of gestational diabetes by use of a glucose polymer

The oral glucose tolerance test is the recommended method for the assessment of carbohydrate metabolism in pregnancy. However, available glucose drinks are often associated with varying degrees of gastrointestinal symptoms that might preclude meaningful studies. Polycose (Ross Labs, Columbus, Ohio) is a glucose saccharide polymer mixture containing 3% glucose, 7% maltose, 5% maltotriose, and 85% polysaccharide of 4 to 15 glucose units, with an osmotic load one fifth that of glucose. We assessed the efficacy of this glucose polymer in the performance of a 3-hour carbohydrate tolerance test with glucose and glucose polymer used 3 to 5 days apart in each patient tested. After 2 days of 300 gm carbohydrate-enriched diets, 48 patients underwent 3-hour carbohydrate tolerance tests at a mean gestational age of 30 +/- 3 weeks. Statistical analysis revealed a moderate level of agreement (kappa = 0.45, p less than 0.001) between the results of both carbohydrate tolerance test preparations. Patients experienced fewer gastrointestinal symptoms with the glucose polymer than with glucose. These preliminary data suggest that glucose polymer may be effectively used in the performance of a 3-hour carbohydrate tolerance test.