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Gestational Diabetes: Symptoms, Diagnosis & Complications

Gestational diabetes is a type of diabetes that is first diagnosed or starts during pregnancy. Similar to type 2 diabetes, it involves insulin resistance and an inability to properly metabolize glucose, the sugar that is the body's main source of energy. Gestational diabetes could be a transient disorder, occurring around second trimester and disappearing postpartum, or a more chronic disease that's somewhat present all along, but exacerbated during the physiological stress of pregnancy, according to the summary and recommendations from the Fifth International Workshop-Conference on Gestational Diabetes Mellitus.

For reasons that are not clear, gestational diabetes occurs more frequently among African Americans, Latin-Americans and American Indians. It occurs in 1 to 5 percent of all pregnancies in the United States, according to the 2007 statistics from the National Institute of Diabetes and Digestive and Kidney Diseases.

A doctor checks a pregnant woman's heart rate with a stethoscope.
Credit: Pregnancy photo via Shutterstock

Symptoms & Causes

Women with gestational diabetes usually have no symptoms or mild, non-life-threatening symptoms, according to the National Institutes of Health. These symptoms are mostly related to abnormal blood sugar levels and can include fatigue, excessive thirst and increased urination.

It's known that the energy requirements of the fetus, weight gain and increased food intake can impose changes in the mother's insulin metabolism. However the exact cause of gestational diabetes is still unknown and has many possible reasons.

It might involve the secretion of human placental lactogen, a hormone produced by the placenta during pregnancy that can alter the way blood sugar is metabolized due to its anti-insulin properties, according to a 2008 article in the journal Reviews and Obstetrics & Gynecology. The placenta also produces insulinase, which facilitates the breakdown of insulin. In addition, changes in estrogen and progesterone during pregnancy might further disrupt the body's glucose-insulin balance.

 

Diagnosis & Tests

Tests for gestational diabetes are usually done around 24 to 28 weeks of pregnancy through the oral glucose tolerance test, according to the NIH. This is the same test used to diagnose type 2 diabetes. In order to prepare for the test, the mother has to fast overnight before her doctor's visit, according to the American Diabetes Association. Her blood is taken before the test, and again in 30- to 60-minute intervals over two to three hours after she drinks a high-glucose solution in order to measure how blood glucose and insulin level changes over time.

Glucose tolerance tests are usually conducted once more at around six to 12 weeks postpartum and then once every one to three years in order to identify any lingering glucose intolerance, according to the CDC.

Complications

Even though most studies conducted in the past 15 years did not find an increase in the perinatal mortality rate, according to the NIH, healthy fetal growth is still an important concern when the mother has gestational diabetes. Abnormally high levels of blood glucose — or hyperglycemia — in the mother would result in more glucose being delivered to the fetus, leading to excessive growth, according to the Fifth International Workshop-Conference on Gestational Diabetes Mellitus. This can lead to birth trauma for the mother, possibly necessitating cesarean delivery, and possible lifelong increased risks of glucose intolerance and obesity in the offspring. Hence, the fetus should be monitored by ultrasound measurement of fetal abdominal circumference starting around the second trimester and repeated every two to four weeks, according to the conference papers.

Postpartum complications for the baby could include low blood sugar, respiratory problems and jaundice, according to the Mayo Clinic.

Even if gestational diabetes disappears after the baby is born, 35 to 60 percent of women can develop type 2 diabetes within 10 years, according to the CDC. Therefore they should be regularly screened for signs of diabetes during later check-ups and be sure to maintain a healthy diet and lifestyle.

Treatments

If diagnosed with gestational diabetes, proper steps will be needed  to maintain normal levels of blood glucose. Special meal plans and regular physical activity can help control blood glucose levels and are often recommended to women with gestational diabetes, according to the American Diabetes Association. In more serious cases, daily blood glucose testing and insulin injections may be required.

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