For Some Overweight Teen Girls, Oral Glucose Tolerance Best Test: Study
For teen girls who are overweight or obese with irregular menstrual cycles, the choice of a test to determine if they have prediabetes and heart disease risk factors is key, according to a Polish researcher.
"If you have adolescent girls who are overweight or obese and in addition have irregular cycles, you should check for cardiovascular risk factors with an oral glucose tolerance test," said Marianna Bak, MD, a researcher at Warsaw Medical University and Endocrinology Outpatient Clinic Children's Memorial Health Institute, Poland. She presented her research at the 14th annual World Congress on Insulin Resistance, Diabetes & Cardiovascular Risk in Universal City, CA. That test is better at detecting problems in these teens than the fasting blood glucose test, which is commonly used, she found.
Dr. Bak evaluated 144 girls, ages 12 to 18, who had irregular menstrual periods. While 80 were obese, 64 were normal weight.
During puberty, Dr. Bak said, a mild amount of insulin resistance (causing blood sugar levels to rise) is normal, but if it continues it can impact heart disease risk. She focused on girls having menstrual cycle irregularities because identifying a subset of girls with a condition called polycystic ovary syndrome, linked with irregular cycles, may help in assessing insulin resistance and heart disease risk. Polycystic ovary syndrome affects fertility, is linked with insulin resistance and over time raises the risk of diabetes and heart disease.
Dr. Bak's team took a medical history, evaluated the teens' endocrine profile, and gave them a fasting blood sugar test and an oral glucose tolerance test (OGTT). The fasting blood sugar test requires a one-time draw of blood after fasting for 12 hours. The OGTT begins with the person fasting, then drinking a sugared drink and having their blood drawn for testing 5 times in all over three hours.
All the girls had a normal fasting blood glucose test, regardless of their body mass index (BMI). However, the oral glucose tolerance test gave a different picture. While 11% of the normal weight teens had an abnormal test, 27% of the obese girls did, Dr. Bak found. Giving obese girls with irregular cycles the more extensive test, Dr. Bak said, will help physicians start treatment when needed to manage the insulin resistance. When teens are obese and have irregular cycles that could reflect PCOS, she said, they have a three-fold higher frequency of having prediabetes, Dr. Bak said. In prediabetes, the body is not using insulin efficiently, although it is not a full-blown diabetes diagnosis.
For teens who are obese and have PCOS, the oral glucose tolerance test is probably the better way to go to detect problems early, said Minisha Sood, MD, director of inpatient diabetes at Lenox Hill Hospital, New York. She reviewed the presentation.
Another test option, she said, is the hemoglobin A1C, which provides a look back at average blood sugar levels over the previous three months. However, Dr. Sood said, the oral glucose tolerance test take more time, which could be a deterrent for some.