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Clinical Benefits Found From Treating Mild Gestational Diabetes

Feb 17, 2009

Treatment of mild gestational diabetes yields clinical benefit, a randomized trial showed. Although a composite endpoint of neonatal morbidity did not differ between the treatment group and the controls, rates of Caesarean delivery (P=0.021) and shoulder dystocia (P=0.019) were significantly reduced by treatment.

In addition, treated women were significantly less likely to develop gestational hypertension or preeclampsia (P=0.015), said Mark Landon, M.D., of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.


“Identification and treatment of mild gestational diabetes is clearly associated with significant clinical benefits,” he said at the Society for Maternal-Fetal Medicine meeting here.

Although there has been a longstanding debate about the clinical significance of mild gestational diabetes on perinatal morbidity, there has been wide acceptance of treating the condition, according to Dr. Landon.  Nevertheless, in both 2003 and 2008, the U.S. Preventive Services Task Force said there was insufficient evidence to recommend treating mild gestational diabetes, he said.  So Dr. Landon and colleagues conducted a multicenter, randomized trial to determine whether an intervention consisting of nutrition management and insulin, if necessary, would reduce maternal and neonatal morbidity.
Women were included in the study if they had a 50-gram glucose test value between 135 and 200 mg% between 24 and 29 weeks gestation, as well as an abnormal three-hour 100-gram oral glucose tolerance test.  Mild gestational diabetes was defined as a fasting glucose greater than 95 mg/dL and abnormal glucose tolerance test results at two of three following time points: one hour (>180 mg/dL), two hours (>155 mg/dL), and three hours (>140 mg/dL).

The researchers randomized 485 women (mean age 29.2; 57% Hispanic) to formal nutrition counseling, self blood glucose monitoring, and insulin if necessary and 473 women (mean age 28.9; 56% Hispanic) to standard obstetric care. The two groups were similar in baseline demographics and glycemic values. The gestational age at delivery was similar in the two groups (P=0.904).

The composite outcome of neonatal morbidity, which included perinatal mortality, hypoglycemia, hyperbilirubinemia, hyperinsulinemia, and birth trauma, occurred at similar rates in the treated (32.4%) and untreated (37%) groups (P=0.143).
Each individual outcome occurred at similar rates as well.  There were no stillbirths or neonatal deaths in either group. However, there were some clinically significant differences between the two groups. Babies born to women in the treated group had a mean birth weight that was about 100 g lower than those born to untreated women (P=0.0005).  The frequency of babies born weighing more than 4,000 grams was significantly lower in the treated group (6% versus 14%, P<0.001). In addition, the frequency of large-for-gestational-age babies was lower in the treatment group (P<0.001).

Rates of small-for-gestational-age babies, admission to the neonatal ICU, preterm delivery, need for IV glucose, respiratory distress syndrome, and transient tachypnea of the newborn were similar between the two groups.

Mothers who were treated had a lower body mass index at delivery (P=0.0007) and gained less weight from randomization to delivery (2.8 versus 5 kg, P<0.0001) than untreated mothers.

“We found that treatment of mild gestational diabetes did not reduce the frequency of several commonly reported morbidities associated with diabetic pregnancy,” Dr. Landon said.

However, he said, the results of the study provide evidence supporting the treatment of mild gestational diabetes.

Practice Pearls:

Explain to interested patients that there has been a longstanding controversy about the effectiveness of treating mild gestational diabetes.

Explain that this study found that, even though neonatal morbidity was not improved, there were several clinically significant benefits to treating mild gestational diabetes.

Landon M, et al “A prospective multicenter randomized treatment trial of mild gestational diabetes (GDM)” SMFM 2009; Abstract 2.