Novel therapies for diabetes mellitus in pregnancyBMJ 2018; 362 doi: https://doi.org/10.1136/bmj.k2034 (Published 16 July 2018) Cite this as: BMJ 2018;362:k2034
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We have read with interest the comprehensive review on novel therapies for diabetes mellitus in pregnancy. We note the observations regarding the variation in the prevalence of gestational diabetes mellitus (GDM) according to the population studied, the diagnostic criteria used and the association of this with the rise in obesity.
However, we believe that more attention needs to be given to the laboratory diagnosis of GDM and in particular, the preanalytical handling of phlebotomy samples. Laboratory standards for the handling of glucose samples in a fluoride buffer tube specify that the sample needs to be placed on an iced-slurry for transport to the laboratory with centrifugation within 30 minutes of phlebotomy. (1,2) If this cannot be adhered to, then a citrate buffer, which is a rapid inhibitor of glycolysis, should be used.
A study of 155 women undergoing selective screening for GDM at 24-32 weeks (with paired samples) reported a rate of GDM of 14.2% (n=22) when usual conditions were applied (3). These samples which remained at room temperature had a mean phlebotomy to analysis interval of 162 minutes (SD 19) for the fasting sample. In the samples that were handled according to the laboratory guidelines, the rate of GDM was 38.1% (n=59) with a mean phlebotomy to analysis interval of 20 minutes (SD 9) for the fasting sample.
We believe that the prevalence of GDM is under-estimated and strict implementation of laboratory standards is paramount for the correct identification of women with GDM and evaluation of all novel therapies both for diagnosis and for monitoring maternal glycaemia.
1. Sacks DB, Arnold M, Bakris GL, Bruns DE, Horvath AR,Kirkman MS, et al. Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus. Diabetes Care 2011;34:e61–99.
2. Daly N, Turner MJ. Laboratory diagnosis of gestational diabetes mellitus. BJOG: An International Journal of Obstetrics & Gynaecology. 2016;123(9):1430-3.
3. Daly N, Flynn I, Carroll C, Farren M, McKeating A, Turner MJ. Impact of implementing preanalytical laboratory standards on the diagnosis of gestational diabetes mellitus: a prospective observational study. Clinical Chemistry. 2016;62(2):387-91.
Competing interests: No competing interests