Gestational Diabetes Mellitus and Frequency of Blood Glucose Monitoring: A Randomized Controlled Trial.

Objective: To assess whether testing blood glucose four times daily compared with four times every other day would lead to similar birth weights among patients with gestational diabetes mellitus (GDM).

Methods: This noninferiority randomized controlled trial was conducted at five centers. After receiving a diagnosis of GDM, women tested their blood glucose every day for 7 days. After that period, compliant women without hyperglycemia requiring treatment were randomized to either blood glucose testing four times a day or every other day. Noninferiority would be declared if the mean birth weight in the every-other-day group was no higher than 165 g (5% difference assuming an average birth weight of 3,296 g) compared with the four times a day group. A total sample size of 286 women allowed noninferiority to be tested (one-sided .05 level of significance).

Results: From May 2013 to May 2016, of the 293 women with GDM who were randomized, 149 (51%) were tested four times a day and 144 (49%) were tested every other day. Between the two groups, there were no significant differences with regard to need for medical treatment, induction, gestational age at delivery, mode of delivery, rate of preeclampsia, or shoulder dystocia. Birth weight was similar between both groups and the upper bound of the 90% confidence interval (CI) was less than 165 g, establishing noninferiority with a mean difference of -41 g (90% CI -137 to 54 g). Rate of compliance with blood glucose testing was higher in the every-other-day group (89% compared with 92%, P<.01). The differences in rates of macrosomia and birth weight greater than the 95th percentile were not clinically significant. Neonatal outcomes including neonatal hypoglycemia were similar.

Conclusion: Among patients with well-controlled GDM, testing blood glucose values every other day did not increase birth weight, although it did increase compliance with testing when compared with women who tested every day.

Clinical Trial Registration: ClinicalTrials.gov, NCT01818557.