Testing pregnant women for insulin resistance with a simple blood test may be a new tool for predicting problems during pregnancy, according to a new study. The results will be presented at The Endocrine Society’s 90th Annual Meeting in San Francisco.

Insulin resistance is a condition in which the body blocks the effects of the hormone insulin. As a result, glucose, or sugar, builds up in the blood, and diabetes can develop. Insulin resistance lies behind the development of gestational diabetes—diabetes that develops during pregnancy—which increases the risk of pregnancy and birth complications. Therefore, the authors aimed to find out whether insulin resistance is linked to poor outcomes in pregnant women and newborns, said the lead author, Weerapan Khovidhunkit, MD, PhD, of Chulalongkorn University, Bangkok, Thailand.

It is standard for pregnant women to get a blood test for gestational diabetes between the 24th and 28th weeks of pregnancy, according to The Hormone Foundation, the public education affiliate of The Endocrine Society. This test is called the glucose challenge test or glucose challenge screening. If this test result is positive, the woman then has an oral glucose tolerance test (OGTT), in which her blood sugar levels are tested 3 hours after she drinks a glucose drink.

“The OGTT is time-consuming,” Khovidhunkit said. “Also, many women cannot tolerate an OGTT due to nausea and vomiting.”

It is possible for women to have high iinsulin resistance without having gestational diabetes, according to Khovidhunkit. A special test of insulin resistance, called HOMA, is not part of standard pregnancy tests, but it is quick and easy, he said. This test relies on a fasting blood test of glucose and insulin levels.

The authors studied 538 pregnant women who had positive glucose challenge tests and then underwent the OGTT. The researchers also assessed insulin resistance using HOMA. They tracked pregnancy complications, including preeclampsia, a condition involving  high blood pressure; excess amniotic fluid (called polyhydramnios); premature rupture of the membranes, in which the woman’s water breaks before she goes into labor; and need for a cesarean section.

Even if women did not have gestational diabetes, those who had the highest degree of insulin resistance (above 2.44) had nearly 1.5 times the rate of pregnancy complications than those with the lowest insulin resistance, the authors found. The most common maternal complication was need for a cesarean section, according to Khovidhunkit.

Similarly, babies born to women in the group that had the highest degree of insulin resistance had a complication rate at birth 1.75 times higher than babies born to women with the lowest insulin resistance. The most common newborn complications were macrosomia—an abnormally large size—as well as low blood sugar (hypoglycemia), the authors reported.

The study tested only pregnant women who were at increased risk of pregnancy complications because they had high blood glucose levels, as shown by a positive glucose challenge test. Therefore, Khovidhunkit said, “Before we can advise pregnant women to undergo this testing, further studies are needed in other patient populations.”

About Type 2 Diabetes 

Type 2 diabetes is also referred to as non-insulin dependent diabetes mellitus (NIDDM), or adult onset diabetes mellitus (AODM). The disease is characterized by high levels of blood sugar, caused by the body's inability to utilize insulin to move blood sugar into the cells for energy. In type 2 diabetes, patients can still produce insulin, but do so relatively inadequately for their body's needs, particularly in the face of insulin resistance as discussed above. In many cases this actually means the pancreas produces larger than normal quantities of insulin.

A major feature of type 2 diabetes is a lack of sensitivity to insulin by the cells of the body (particularly fat and muscle cells). In addition to the problems with an increase in insulin resistance, the release of insulin by the pancreas may also be defective and suboptimal. High plasma levels of insulin and glucose due to insulin resistance often lead to metabolic syndrome and type 2 diabetes, including its complications.