High probability of false-positive gestational diabetes mellitus diagnosis during early pregnancy

Abstract

IntroductionThis study aimed to assess the validity of applying the International Association of Diabetes and Pregnancy Study Group (IADPSG) criteria for the diagnosis of gestational diabetes mellitus (GDM) at any time during pregnancy.Research design and methodsThis multicenter cohort study was conducted at five Japanese facilities from January 2018 to April 2019. The study cohort included women at a high risk of GDM who met one or more of the following IADPSG criteria during early pregnancy: fasting plasma glucose (FPG) ≥92 mg/dL and 75 g oral glucose tolerance test (OGTT) value of ≥180 mg/dL at 1 hour, or ≥153 mg/dL at 2 hour (hereafter early-onset GDM). Women diagnosed with early-onset GDM were followed up without therapeutic intervention and underwent the 75 g OGTT again during 24–28 weeks of gestation. Those exhibiting the GDM patterns on the second 75 g OGTT were diagnosed with true GDM and treated, whereas those exhibiting the normal patterns were diagnosed with false positive early GDM and received no therapeutic intervention.ResultsOf the 146 women diagnosed with early-onset GDM, 69 (47%) had normal 75 g OGTT values at 24–28 weeks of gestation, indicating a false-positive result. FPG levels were significantly higher in the first 75 g-OGTT test than in the second 75 g-OGTT test (93 mg/dL and 87.5 mg/dL, respectively; p<0.001). FPG levels were high in 86 (59%) women with early-onset GDM during early pregnancy but in only 39 (27%) women during mid-pregnancy. Compared with false positive early GDM, true GDM was more frequently associated with adverse pregnancy outcomes.ConclusionsAlthough women with early-onset GDM were followed up without treatment, the results of repeated 75 g OGTT during mid-pregnancy were normal in about 50%. Our data did not support the adoption of IADPSG thresholds for the diagnosis of GDM prior to 20 weeks of gestation.

Screening for Gestational Diabetes Mellitus in Early Pregnancy: What Is the Evidence?

“…Of all observational studies ( Table 1 ), 15 studies discussed the diagnostic criteria for GDM early in pregnancy [ 11 , 12 , 13 , 14 , 16 , 18 , 21 , 24 , 26 , 27 , 28 , 31 , 32 , 35 , 36 ]. Riskin et al showed that first trimester fasting glucose levels (FTFPG) in the non-diabetic range resulted in a higher risk for adverse pregnancy outcomes, such as more cesarian sections, LGA and macrosomia.…”

A prospective cohort study of postpartum glucose metabolic disorders in early versus standard diagnosed gestational diabetes mellitus

“…Fasting glycaemia was tested on venous samples in laboratories conforming with standard practice, negating the need for rechecking at the hospital. Recently, Nakanishi et al found that women with positive OGTT results taken before 20 WG showed normal results by 24-28 WG in 47% 22 , as previously shown 6,7 . However, the discrepancies between the early and later tests were particularly marked for women where only the fasting result was abnormal in the early test.…”

Impact of gestational diabetes mellitus diagnosed during the third trimester on pregnancy outcomes: a case-control study

“…It remains unknown whether the IADPSG criteria developed based on the results of the HAPO study of pregnant women between 24 and 32 weeks of gestation can be applied to different weeks of gestation to correctly detect abnormal glucose tolerance or pregnant women at high risk. Furthermore, OGTT results have been reported to vary according to the weeks of gestation [ 15 , 16 ].…”