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Study author Dr. Erica Berggren, talks to 2 Minute Medicine: Maternal Fetal Medicine Specialist at Jefferson Medical College

“Our findings of minimal differences by race/ethnicity is clinically relevant, as our data do not support tailored diagnostic criteria or treatment for Hispanic women, among women with mild hyperglycemia.”

Key study points: 

1. Poor glycemic control in gestational diabetes is associated with adverse maternal and fetal outcomes.

2. Across treatment groups, Hispanic and non-Hispanic groups experienced very similar perinatal outcomes.

Primer: Pregnancy is a state of increased insulin resistance, owing to high estrogen and various placental hormones (cortisol, placental growth hormone, progesterone, etc) and peaks in the third trimester. However, some pregnant women go on to develop glucose intolerance or gestational diabetes (GDM). Certain demographic groups (e.g. overweight, obese and Hispanic women) are at higher risk for developing GDM (1-2).

In women with GDM, poor glucose control increases risk for both adverse maternal and fetal outcomes. Women with GDM are more likely to develop hypertensive disorders of pregnancy (e.g. gestational hypertension, pre-eclampsia, eclampsia) and their fetuses are more likely to be macrosomic, increasing their risk for hyperbilirubinemia and birth trauma (3).

Customary screening in the U.S. is to perform the 50-gram 1-hour oral glucose challenge test at 24-28 weeks gestation. Blood glucose values greater than 135mg/dL suggest glucose intolerance and values greater than 200mg/dL concern for frank diabetes. Women with abnormal screening tests will undergo the 100-gram 3-hour oral glucose tolerance test (OGTT), with a positive result defined as at least two blood glucose values taken at 1-hour increments (fasting, 1-hour, 2-hour, 2-hour) that exceed threshold values (Table 1) (1).

Table 1. Two diagnostic criteria for the OGTT to diagnose GDM

Status	Plasma Glucose Level (Carpenter/Coustan Conversion)		Plasma Glucose Level (National Diabetes Data Group)
	mg/dL	mmol/L	mg/dL	mmol/L
Fasting	95	5.3	105	5.8
One hour	180	10.0	190	10.6
Two hours	155	8.6	165	9.2
Three hours	140	7.8	145	8.0

    Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care 2000;23(suppl 1):S4–S19.

Hispanic women are at higher risk for GDM, but it remains unknown whether perinatal outcomes among Hispanic women with glucose intolerance or GDM differ from those in non-Hispanic women. The present work addressed this question by comparing perinatal outcomes between Hispanic and non-Hispanic white women with glucose intolerance or mild GDM.

Background reading: 

1. ACOG’s FAQ on gestational diabetes

2. Up-to-date: Screening and diagnosis of diabetes mellitus during pregnancy

3. Gestational Diabetes. ACOG Practice Bulletin No. 30. American College of Obstetricians and Gynecologists. Obstet Gynecol 2001;98:525–538

This [secondary analysis of a randomized clinical trial] compared perinatal outcomes in women with glucose intolerance or mild gestational diabetes mellitus by ethnicity/racial group (Hispanic or non-Hispanic women).

Among women with glucose intolerance, Hispanic women had increased odds of having a neonate with elevated C-cord peptide (a marker of fetal insulinemia) (OR 1.79, CI: 1.04-3.08) and neonatal hypoglycemia (OR 2.04 CI 1.18-3.53). In women with mild GDM randomized to no treatment, outcomes were similar. In women with mild GDM randomized to treatment, Hispanic women were at increased odds of having a neonate with hyperinsulinemia (OR 2.96, CI 1.33-6.60).

In sum: Most perinatal outcomes were similar between Hispanic and non-Hispanic ethnic groups with glucose intolerance or mild gestational diabetes. To conclude that outcomes differ by ethnicity, we would expect a number of related markers to manifest this difference (e.g. fetal hypoglycemia, hyperinsulinemia and high c-cord peptide). Thus, it is likely that the individual differences observed are not representative of a clinically meaningful difference in perinatal outcomes by ethnicity.

Click to read this article in the current issue of Obstetrics & Gynecology

By [LH]

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