Metformin was found to be better than insulin at controlling blood glucose after some meals in women with gestational diabetes, and was also linked to advantages in certain pregnancy-related outcomes in a new study published in the American Journal of Obstetrics and Gynecology.
Insulin has long been the standard treatment for gestational diabetes in women who can’t adequately control their blood glucose through physical activity and dietary changes. But several studies in recent years have suggested that metformin may be a viable alternative to insulin, leading to a similar reduction in blood glucose without carrying some of the risks associated with insulin, such as hypoglycemia (low blood glucose) and weight gain. But certain clinical guidelines for treating gestational diabetes still don’t endorse prescribing metformin instead of insulin, and it’s unknown how commonly it’s prescribed for gestational diabetes.
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For the latest study, researchers wanted to see if metformin could achieve the same effect as insulin on blood glucose control in women with gestational diabetes, as well as if it was safe — which included looking at results related to childbirth and both maternal and infant health. The study participants were 200 women, ages 18 to 45, who had gestational diabetes and were in their second or third trimester of pregnancy. Half of the women were randomly assigned to take insulin, and half were assigned to take metformin. The main outcomes the researchers were interested in were overall blood glucose control, after-meal glucose control, episodes of hypoglycemia, and pregnancy-related outcomes and complications including hypertensive disorders (related to high blood pressure), premature delivery, large birth weight for gestational age, and admission to the neonatal intensive care unit (NICU).
Metformin found to have benefits in gestational diabetes
The researchers found that average fasting and post-meal blood glucose levels were nearly identical between the insulin and metformin groups. After lunch or dinner, though, blood glucose levels were significantly lower in the metformin group. Not surprisingly, more women in the insulin group experienced hypoglycemia during the course of treatment — 55.9%, compared with 17.7% in the metformin group. Women in the metformin group gained less weight between the start of the study and their prepartum study visit, 36 or 37 weeks into their pregnancy — an average weight gain of 1.35 kilograms (2.98 pounds), compared with 3.87 kilograms (8.53 pounds) in the insulin group. Labor had to be induced more often in the insulin group — 62.5% of the time, compared with 45.7% in the metformin group. Caesarean delivery was also significantly more common in the insulin group, occurring in 52.6% of deliveries, compared with 27.6% in the metformin group. There weren’t any significant differences between the two groups when it came to various pregnancy complications and outcomes, including those related to birth weight.
“Metformin treatment was associated with a better postprandial glycemic control than insulin for some meals, a lower risk of hypoglycemic episodes, less maternal weight gain, and a low rate of failure as an isolated treatment,” the researchers concluded. “Most obstetrical and perinatal outcomes were similar between groups,” indicating that metformin may be a good alternative to insulin for treating gestational diabetes in many situations.
Want to learn more about gestational diabetes? Read “Glucose Test During Pregnancy for Gestational Diabetes,” “Treatment for Gestational Diabetes: Once You’re Diagnosed,” and “Gestational Diabetes: More Treatment Approaches.”