Sensitivity of fasting glucose for gestational diabetes mellitus screening in Mexican adolescents based on International Association of Diabetes and Pregnancy Study Groups criteria: a diagnostic accuracy study based on retrospective data analysis

Abstract

Objective: To evaluate fasting plasma glucose (FPG) as a screening test for gestational diabetes mellitus (GDM) among Mexican adolescents using International Association of Diabetes and Pregnancy Study Groups criteria.

Design: Retrospective cohort study.

Setting: Level-three medical institution in Mexico City.

Participants: The study population comprised 1061 adolescent women aged 12-19 years with singleton pregnancies, who underwent a 75 g oral glucose tolerance test (OGTT) between 11 and 35 weeks of gestation.

Primary and secondary outcome measures: The sensitivity (Sn), specificity (Sp), positive and negative predictive values (PPV and NPV, respectively), and positive and negative likelihood ratios LR (+) and LR (-), respectively) with 95% CIs for selected FPG cut-off values were compared. Secondary measures were perinatal outcomes in women with and without GDM.

Results: GDM was present in 71 women (6.7%, 95% CI 5.3% to 8.4%). The performances of FPG at thresholds of ≥80 (4.5 mmol/L), 85 (4.7 mmol/L) and 90 mg/dL (5.0 mmol/L) were as follow (95% CI): Sn: 97% (89% to 99%), 94% (86% to 97%) and 91% (82% to 95%); Sp: 50% (47% to 53%), 79% (76% to 81%) and 97% (95% to 97%); PPV: 12% (9% to 15%), 23% (18% to 28%) and 64% (54% to 73%); NPV: 99% (98.5% to 99.9%) for all three cut-offs; LR (+): 1.9 (1.8 to 2.1), 4.3 (3.8 to 5.0) and 26.7 (18.8 to 37.1) and LR (-): 0.06 (0.02 to 0.23), 0.07 (0.03 to 0.19) and 0.09 (0.04 to 0.19), respectively. No significant differences in perinatal outcomes were found between adolescents with and without GDM.

Conclusions: An FPG cut-off of ≥90 mg/dL (5.0 mmol/L) is ideal for GDM screening in Mexican adolescent women. An FPG threshold of 90 mg/dL would miss 6 (8.5%) women with GDM, pick up 34 (3.4%) women without GDM and avoid 962 (90.7%) OGTTs.

Keywords: IADPSG; adolescent; gestational diabetes; hyperglycaemia; pregnancy.