Accuracy of point‐of‐care HbA1c testing in pregnant women

Relationship Between Time-in-Range, HbA1c, and the Glucose Management Indicator in Pregnancies Complicated by Type 1 Diabetes

Objective: We aimed to evaluate relationships between time-in-range (TIR 63-140 mg/dL), glycated hemoglobin A1c (HbA1c) level, and the glucose management indicator (GMI) in pregnant women with type 1 diabetes. Research Design and Methods: Continuous glucose monitoring (CGM) data from 27 women with type 1 diabetes were collected prospectively throughout pregnancy. Up to 90-days of CGM data were correlated with point-of-care HbA1c levels measured in the clinic at each trimester. GMI levels were calculated using a published regression formula. Liner models were used to compare TIR, HbA1c, and GMI by each trimester. Results: There was a significant negative correlation between TIR and HbA1c; each 10% increase in TIR was associated with a 0.3% reduction in HbA1c. The correlation between TIR and HbA1c was stronger (r = -0.8) during the second and third trimesters than during the first trimester (r = -0.4). There was good correlation between TIR and GMI during each trimester (r = 0.9 for each trimester). The relationship between GMI and HbA1c especially during second (r = 0.8) and third trimesters (r = 0.8) was strong. Conclusion: In the first trimester, the correlation between HbA1c level and TIR was relatively small, while that of TIR and GMI was very strong, thus GMI may better reflect glycemic control than HbA1c in early pregnancy. Each 10% increase in TIR was associated with a 0.3% reduction in HbA1c throughout pregnancy, which was lower than other published studies in nonpregnant populations reporting a 0.5%-0.8% reduction in HbA1c. Further studies are needed to understand the relationship between TIR and GMI and how GMI may affect maternal and fetal complications. Clinical Trial Registration number: NCT02556554.

The Pacific-specific CREBRF rs373863828 allele protects against gestational diabetes mellitus in Māori and Pacific women with obesity

AIMS/HYPOTHESIS

The CREBRF rs373863828 minor (A) allele is associated with increased BMI but reduced prevalence of type 2 diabetes in Māori and Pacific people. Given the shared aetiology of type 2 diabetes and gestational diabetes mellitus (GDM), we tested for an association between the CREBRF rs373863828 variant and GDM.

METHODS

We conducted a prospective cohort study of Māori and Pacific women nested within a nutritional intervention study for pregnant women with obesity. Women were enrolled at 12-17 weeks' gestation and underwent anthropometry and collection of buffy coats for later genetic testing. GDM was diagnosed by 75 g OGTT at 24-28 weeks' gestation using the International Association of Diabetes and Pregnancy Study Groups criteria. Genotyping was performed by real-time PCR with a custom CREBRF rs373863828 probe-set. The association between CREBRF rs373863828 and GDM was analysed separately by ethnic group using logistic regression, with effect estimates combined in a meta-analysis.

RESULTS

Of 112 Māori and Pacific pregnant women with obesity, 31 (28%) carried the CREBRF rs373863828 A allele (A/G or A/A) and 35 (31%) developed GDM. Women who carried the CREBRF rs373863828 A allele did not differ in BMI when compared with non-carriers (G/G). There was a fivefold reduction in the likelihood of GDM per CREBRF rs373863828 A allele (OR 0.19 [95% CI 0.05, 0.69], p = 0.01), independent of age, BMI and family history of diabetes (adjusted OR 0.13 [95% CI 0.03, 0.53], p = 0.004). GDM was diagnosed in 10% and 40% of women with and without the CREBRF rs373863828 A allele, respectively (no woman with the A/A genotype developed GDM).

CONCLUSIONS/INTERPRETATION

The CREBRF rs373863828 (A) allele is associated with reduced likelihood of GDM in Māori and Pacific women with obesity and may improve GDM risk prediction. Graphical abstract.