Postpartum testing for antecedent gestational diabetes

Testing for gestational diabetes

In 1996, the American Diabetes Association reported that 12% of total health care expenditure in the United States was spent on diabetes and its complications. Screening for and treating gestational diabetes results in improved perinatal morbidity and mortality. Moreover, detecting gestational diabetes identifies women who are at risk of future type 2 diabetes. This article reviews several approaches to diagnosing gestational diabetes.

Postpartum oral glucose tolerance tests in mothers of macarosomic infants: inadequacy of current antenatal test criteria in detecting prediabetic state

OBJECTIVE

To assess the presence of subtle carbohydrate metabolism abnormalities in otherwise healthy mothers who have given macrosomic birth by utilizing postpartum oral glucose tolerance test (PPOGTT).

STUDY DESIGN

Prospective controlled study enrolled gestational diabetic women (GDM, n=10), mothers with macrosomic infants (MwMIs, n=62) and controls (n=50).

RESULTS

Receiver operating characteristic (ROC) curve analysis revealed that incremental 1-h+2-h PPOGTT value >111 mg/dl had a sensitivity of 80% and specificity of 78% in predicting antecedent diabetes. PPOGTT results were positive in 53.2% of MwMIs and 28% of controls (P<0.01). Maternal low-density lipoprotein and triglyceride levels, 50 gram glucose challenge test (50 g GCT) values and neonatal weight were the significant predictors of PPOGTT results. ROC analyses suggested that threshold of 50 g GCT should be lowered in order to better predict subjects with both macrosomia and positive PPOGTT.

CONCLUSION

PPOGTT may identify a subset of women with macrosomic infants who have metabolic alterations of a prediabetic state. The discrepancies between antenatal and postpartum tests may reflect the need for redefinition of currently utilized criteria in screening and diagnosis of GDM.

Prostanoid production in the umbilicoplacental arterial tree relative to impaired glucose tolerance

The purpose of this study was to investigate prostanoid synthesis in different segments of the umbilicoplacental vascular tree and its relationship to impaired maternal glucose tolerance. Segments from the umbilical artery and vein, allantochorionic artery branches, and the cotyledon artery from 21 women with diabetes or impaired glucose tolerance and 10 healthy women were studied. Production of prostacyclin (PGI2) and thromboxane (TxA2) metabolites was determined. The Mann-Whitney U test, Wilcoxon signed-ranks matched-pairs test, Kruskal-Wallis test, analysis of variance, and simple linear regression analysis were used. A two-tailed P value of < 0.05 was considered statistically significant. From the umbilical artery distal to the cotyledon artery, the PGI2 synthesis decreased and the TxA2 synthesis increased gradually towards the periphery in normal pregnancy. The PGI2/TxA2 ratio was more than 200 times higher in the umbilical artery than in the cotyledon artery. The TxA2 production tended in general to be higher in the diabetic group than in the control group, resulting in significantly lower PGI2/TxA2 ratios in some vessels. The prostanoid production was not significantly correlated to maternal HbA1c or cord C-peptide concentrations. The balance between vascular prostacyclin and thromboxane synthesis in the umbilicoplacental arterial tree changed gradually towards the periphery: the more peripheral, the lower the prostacyclin and the higher the thromboxane production. The physiological role of this phenomenon is unknown, but may be of importance for the equilibration of vascular tone between arteries of different calibers. The altered prostanoid balance found in diabetic pregnancy was not directly attributable to the degree of maternal glycemic control, but may reflect increased free radical activity and peroxide production in diabetes.

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.