Effects of Changing Diagnostic Criteria for Gestational Diabetes Mellitus in Queensland, Australia

OBJECTIVE: To evaluate the effects of updated gestational diabetes mellitus (GDM) screening and diagnostic criteria on selected perinatal outcomes in Queensland, Australia. METHODS: This was a pre-post comparison study using perinatal data the year before (2014) and after (2016) the screening and diagnostic criteria for GDM was changed in Queensland, Australia. In 2015, Queensland adopted the one-step screening and diagnostic criteria based on the International Association of the Diabetes and Pregnancy Study Groups' recommendations. The data from 62,517 women in 2014 and 61,600 women in 2016 who gave birth from 24 weeks of gestation were analyzed in three groups in each year: women with GDM; women without diagnosed GDM; and total population. The outcome measures were gestational hypertension, cesarean birth, gestational age at delivery, birth weight, preterm delivery, large-for-gestational age (LGA) neonates, small-for-gestational-age (SGA) neonates, neonatal hypoglycemia, and respiratory distress. RESULTS: The diagnosis of GDM increased from 8.7% (n=5,462) to 11.9% (n=7,317). After changing the diagnostic criteria, the changes to outcomes, odds ratios (OR), and adjusted odds ratios (aOR) (95% CI) for outcomes with statistically significant differences for the total population were: gestational hypertension 4.6% vs 5.0%, OR 1.09 (1.03-1.15), aOR 1.07 (1.02-1.13); preterm birth 7.6% vs 8.0%, OR 1.05 (1.01-1.09), aOR 1.06 (1.02-1.10); neonatal hypoglycemia 5.3% vs 6.8%, OR 1.31 (1.25-1.37), aOR 1.32 (1.25-1.38); and respiratory distress 6.2% vs 6.0%, OR 0.96 (0.91-1.00), aOR 0.94 (0.89-0.99). There was no change to cesarean births or LGA or SGA neonates for women with or without diagnosed GDM or the total population. CONCLUSION: Except for a very small decrease in respiratory distress, changing the diagnostic criteria has resulted in more GDM diagnoses with no observed changes to measured perinatal outcomes for women with and without diagnosed GDM.</p

Gestational diabetes mellitus screening and diagnosis criteria before and during the COVID-19 pandemic: a retrospective pre–post study

Objective: To determine whether perinatal outcomes after excluding gestational diabetes mellitus (GDM) on the basis of fasting venous plasma glucose (FVPG) assessment during the coronavirus disease 2019 (COVID-19) pandemic in 2020 were similar to those during the preceding year after excluding GDM using the standard oral glucose tolerance test (OGTT) procedure. Design: Retrospective pre–post study. Setting, participants: All women who gave birth in Queensland during 1 July – 31 December 2019 and 1 July – 31 December 2020. Main outcome measures: Perinatal (maternal and neonatal) outcomes for pregnant women assessed for GDM, by assessment method (2019: OGTT/glycated haemoglobin [HbA1c] assessment; 2020: GDM could be excluded by an FVPG value below 4.7 mmol/L). Results: 3968 of 29 113 pregnant women in Queensland during 1 July – 31 December 2019 (13.6%) were diagnosed with GDM, and 4029 of 28 778 during 1 July – 31 December 2020 (14.0%). In 2020, FVPG assessments established GDM in 216 women (1.1%) and excluded it in 1660 (5.8%). The frequencies of most perinatal outcomes were similar for women without GDM in 2019 and those for whom it was excluded in 2020 on the basis of FVPG values; the exception was caesarean delivery, for which the estimated probability increase in 2020 was 3.9 percentage points (95% credibility interval, 2.2–5.6 percentage points), corresponding to an extra 6.5 caesarean deliveries per 1000 births. The probabilities of several outcomes — respiratory distress, neonatal intensive care or special nursery admission, large for gestational age babies — were about one percentage point higher for women without GDM in 2020 (excluding those diagnosed on the basis of FVPG assessment alone) than for women without GDM in 2019. Conclusions: Identifying women at low absolute risk of gestational diabetes-related pregnancy complications on the basis of FVPG assessment as an initial step in GDM screening could reduce the burden for pregnant women and save the health system substantial costs.</p