QUEBEC CITY — The fasting plasma glucose test is inadequate, compared with the oral glucose tolerance test, in screening high-risk pediatric patients for type 2 diabetes and prediabetes, according to results of a new study.
“This is further evidence that impaired fasting glucose and impaired glucose tolerance are two distinct entities,” said Stasia Hadjiyannakis, M.D., a pediatric endocrinologist at Children's Hospital of Eastern Ontario in Ottawa.
The study included 152 children aged 5-18 years (mean age 13 years), who underwent a 2-hour oral glucose tolerance test (2h OGTT) and a fasting plasma glucose (FPG) test.
The children were referred for the tests for evaluation of a number of conditions, including obesity, irregular menses, hirsutism, dyslipidemia, and/or acanthosis nigricans, said Dr. Hadjiyannakis, who reported the findings at the joint annual meeting of the Canadian Diabetes Association (CDA) and the Canadian Society of Endocrinology and Metabolism.
American Diabetes Association guidelines recommend the FPG test alone as the initial screening test for pediatric type 2 diabetes and prediabetes.
But recent studies suggest that even children with normal FPG values can have abnormal 2h OGTT results—indicating impaired glucose tolerance, even though the fasting plasma glucose level is normal.
“If you only screen them with the FPG test, you would miss picking up this abnormality,” Dr. Hadjiyannakis told this newspaper.
Her study found that of the 152 children who underwent the 2h OGTT and the FPG test, 130 (86%) had normal results on both.
Of the 22 with abnormal results, 13 had abnormal FPG levels that would have been picked up by an FPG screening test alone.
But the remaining nine children had normal FPG levels (defined in this Canadian study by CDA criteria of 5.7 mmol/L [103 mg/dL] or greater).
Eight of these children had 2h OGTT levels between 7.8 and 11 mmol/L (140-199 mg/dL), defined as impaired glucose tolerance. One child had a level greater than 11.1 mmol/L (above 200 mg/dL), defined as type 2 diabetes.
If they had been screened with the FPG test alone, 9 of 13 (73%) of those with impaired glucose tolerance and 1 of 2 (50%) of those with type 2 diabetes would have been missed, Dr. Hadjiyannakis said.
She said the study results suggest that in high-risk children, physicians should consider screening with both the FPG test and the OGTT.