WHO criteria ineffective for identifying gestational diabetes mellitus

WHO criteria ineffective for identifying gestational diabetes mellitus | Image Credit: © interstid - © interstid - stock.adobe.com.

According to a recent study published in BMJ Medicine, the 2013 WHO criteria for gestational diabetes mellitus (GDM) has low sensitivity when evaluating a 75 g oral glucose tolerance test (OGTT) in low-risk early pregnancies.

An increase in the prevalence of pregnancies complicated by GDM has been observed worldwide, with 2% to 30% of pregnancies impacted. Changes in screening thresholds have been partially indicated as a reason for this increase. A diagnosis of GDM is determined by neonatal adverse outcome risk, which increases based on maternal hyperglycemia.

A 75 g OGTT is applied at 24 to 28 weeks of gestation to determine maternal hyperglycemia, with diagnostic cutoffs of 5.1 to 6.9 mmol/L for fasting glucose concentrations, 10 or more mmol/L for 1-hour postload plasma glucose concentrations, and 8.5 or more mmol/L for 2-hour concentrations. These criteria were adopted by the WHO in 2013.

To evaluate the WHO 2013 criteria in early pregnancy, investigators conducted a multicenter cohort study. Participants were aged 18 to 45 years, in early pregnancy, and receiving first trimester screening. Gestational age was determined based on the first trimester scan.

Exclusion criteria included pre-existing diabetes, chronic infectious diseases, chronic liver, kidney, or heart disease, prior bariatric surgery, and receiving metformin or acetylsalicylic acid for a history of hypertensive disease in a prior pregnancy. Fetal exclusion criteria included genetic, chromosomal, or morphological abnormalities needing further clarification.

Participant data collected included family history, weight, height, parity, gravidity, urine dipstick, blood pressure, and medical complications. Clinical data included inpatient stays, prenatal care visits, delivery details, and postpartum visits.

Participants at 12 to 15 weeks of gestations received screening with the 75 g OGTT. During the 2 days prior to screening, participants were told to eat and drink as normal. However, on the morning of the test, patients were told not to smoke, eat, or drink more than a few sips of water. 

After a fasting period of at least 10 hours, the first serum glucose levels measurement was performed. One hour and 2-hourpostload blood samples were taken after intake of a 75 g glucose load through 250 to 300 mL of water. GDM was determined by at least 1 abnormal value based on the WHO 2013 criteria.

There were 636 participants included in the final analysis, 12% of which were diagnosed with GDM by a late OGTT. A higher median pre-gravid body mass index and body mass index at the study visit were seen in patients with GDM compared to those without GDM. Maternal age, parity, gravidity, and gestational age at the study visit were similar between both groups.

Of OGTT results, 7.6% were abnormal based on the WHO 2013 criteria. Participants diagnosed with GDM at 24 to 28 weeks of gestation often had higher glucose levels in the early OGTT.

A moderate correlation was found between early and late OGTT. A GDM diagnosis was given to 25.1% of participants using the WHO 2013 criteria for fasting glucose level measurements. The criteria had a low sensitivity and high specificity in early pregnancy.

These results indicated a need to modify the WHO 2013 criteria to detect a later diagnosis of GDM in pregnant individuals. Investigators recommended further research be conducted to validate these findings in different populations and investigate the effects of early lifestyle and drug interventions in managing an early GDM diagnosis vs a late diagnosis.

Reference

Huhn EA, Göbl CS, Fischer T, et al. Sensitivity, specificity, and diagnostic accuracy of WHO 2013 criteria for diagnosis of gestational diabetes mellitus in low risk early pregnancies: international, prospective, multicentre cohort study. BMJ Med. 2023;2(1):e000330. doi:10.1136/bmjmed-2022-000330