Neonatal Birth Weight With Daily Compared With Every-Other-Day Glucose Monitoring in Gestational Diabetes Mellitus: A Randomized Controlled Trial

OBJECTIVE

To assess whether universal use of every-other-day glucose monitoring in patients with gestational diabetes mellitus (GDM) resulted in similar birth weights and medication use and was preferred by the patient compared with traditional daily glucose monitoring.

METHODS

This was a noninferiority randomized controlled trial conducted at a single New York City hospital between April 2021 and May 2022. Patients with singleton pregnancies who were diagnosed with GDM after 20 weeks of gestation and had a minimum of 7 days of previous daily blood glucose testing were randomly assigned to test blood glucose values daily or every other day. The primary outcome was neonatal birth weight. We calculated a total sample size of 196 participants needed for noninferiority to be tested, assuming the mean birth weight in the every-other-day group, compared with the daily group, was no higher than the predefined noninferiority margin of 200 g (80% power and one-sided alpha of 0.05). Postrandomization characteristics, including blood glucose values and medication initiation and timing, were recorded. Satisfaction with treatment group was assessed using the validated Oxford Maternity Diabetes Treatment Satisfaction Questionnaire.

RESULTS

A total of 197 patients were randomized: 98 in the daily group and 99 in the every-other-day group. Baseline characteristics were similar between groups. The mean neonatal birth weight was similar between groups (mean±SD 3,090±418 g among newborns in the daily group compared with 3,181±482 g among newborns in the every-other-day group). For the primary outcome, the every-other-day group was found to be noninferior to the daily group with an upper confidence limit for the mean difference in mean birth weight of 197 g, which was below the noninferiority margin of 200 g (P=.046). Postrandomization, there were no significant differences in the number of patients who required medication, the gestational age at which medication was started, or the type of medication used. Average fasting and postprandial glucose values were similar between groups. There was an increase in adherence to treatment group in those randomized to every-other-day blood sugars, but no difference in patient satisfaction.

CONCLUSION

In patients with GDM, testing blood glucose values every other day was as effective as testing daily, without apparent effects on birth weight, medication initiation, or glucose control. Reduced frequency of blood glucose monitoring might help decrease the emotional, physical, and financial burden experienced by patients with GDM.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT04857073.

Comparison of an intermittently scanned (flash) continuous glucose monitoring system to standard self-monitoring of capillary blood glucose in gestational diabetes mellitus

Objective Gestational diabetes mellitus (GDM) requires close surveillance of blood glucose to prevent perinatal morbidity. Self-monitoring of capillary blood glucose (BGM) comes with considerable psychosocial burden. Intermittently scanned CGM (isCGM) devices are discreet and could considerably impact the lifestyle of the patient. They are designed to replace BGM testing in nonpregnant patients. Data on this technology in pregnancy is scant. The aim of this study was to assess concordance of BGM with isCGM in GDM. Methods IRB approved prospective single arm study evaluating agreement of isCGM (Freestyle Libre 14 day system) compared to BGM when determining glucose levels fasting and 2 hours postprandial for 14 days. This was documented as percentage of results within Zone A (clinically accurate measurements with no effect on clinical action) or Zone B (values that deviate from reference by >20% but would lead to benign/no treatment) of the Parkes Error Grid (developed for non-pregnant patients with diabetes). Per International Organization for Standardization (ISO) criteria, agreement was defined as >95% within Zone A or B. Analytical agreement was evaluated using mean and median absolute relative difference (ARD), mean and median absolute difference (AD). Results There were 1604 pairs of BGM/isCGM observations for 41 patients. Mean glucose values were 102.0 (SD 20.5) mg/dL and 89.4 (SD 20.1) mg/dL for BGM and isCGM, respectively. Mean and median AD were 15.9 and 13.0 mg/dL, respectively. Mean and median ARD were 15.9% and 12.5%, respectively. Zones A and B contained 76.9% and 22.9% of values, respectively, in the Parkes Error Grid, for a total of 99.8%. Conclusions BGM and isCGM demonstrate clinical agreement. However, glucose values with isCGM trended lower, with greater mean and median ARD than prior studies. Given the strict glycemic control required during pregnancy, physicians should be aware of these differences and their possible clinical implications.