Diabetes Dialogue: GLAM and CRISTAL, Updates in Pregnancy

In this episode of Diabetes Dialogue: Technology, Therapeutics, & Real-World Perspectives, hosts Diana Isaacs, PharmD, an endocrine clinical pharmacist, director of Education and Training in Diabetes Technology, and codirector of Endocrine Disorders in Pregnancy at the Cleveland Clinic, and Natalie Bellini, DNP, program director of Diabetes Technology at University Hospitals Diabetes and Metabolic Care Center, provide their audience with an overview of a pair of new studies on the topic of diabetes in pregnancy: the GLAM and CRISTAL studies.

GLAM

Led by investigators at the Maternal Fetal Medicine Research Program at the Perelman School of Medicine, the GLAM study was launched to characterize glucose levels during uncomplicated pregnancies in early pregnancy, which was defined as having an HbA1c less than 5.7% and without a large-for-gestational-age birth, hypertensive disorders of pregnancy, or gestational diabetes mellitus.¹

The study enrolled 937 pregnant individuals aged 18 years and older prior to reaching 17 gestational weeks. All patients received Dexcom G6 continuous glucose monitoring(CGM) devices for use throughout the study. In total, 413 individuals had an uncomplicated pregnancy. This cohort had a mean age of 32 (SD, 4) years, mean BMI of 25.3 (SD, 5.0) kg/m2, and median CGM use of 123 days.¹

Results of the study indicated those with uncomplicated pregnancies had an overall mean glucose during gestation of 98 (SD, 7) mg/dL (5.4 [SD, 0.4] mmol/L), median percent time in range of 63 to 120 mg/dL of 86% (IQR, 82 to 89), median percent of time less than 63 mg/dL of 1.8%, median percent of time greater than 120 mg/dL of 11%, and median percent of time greater than 140 mg/dL of 2.5%.¹

CRISTAL

A double-arm, parallel-group, open-label, randomized controlled trial conducted at a dozen sites, the CRISTAL trial was aimed at assessing the the use of advanced hybrid closed loop (AHCL) therapy with the MiniMed 780G relative to standard insulin therapy among pregnant women with type 1 diabetes. A total of 95 women aged 18 to 45 years with type 1 diabetes underwent randomization at a median of 10.1 (IQR, 8.6 to 11.6) weeks of gestation.²

The primary outcome of interest for the trial was proportion of time spent in the pregnancy-specific target glucose range of 3.5 to 7.8 mmol/L at 14–17 weeks, 20–23 weeks, 26–29 weeks, and 33–36 weeks. For the purpose of analysis, glucose values were measured using CGM. Secondary outcomes of interest included overnight time in target range as well as time below glucose range overall and overnight.²

Upon analysis, results indicated the mean proportion of time spent in the target range was 66.5% (SD, 10.0) in the AHCL therapy group and 63.2% (SD, 12.4) in the standard insulin therapy group (adjusted mean difference, 1.88 percentage points; 95% CI, –0·82 to 4.58; P = .17). Further analysis demonstrated results favored use of AHCL for overnight time in target range (adjusted mean difference, 6.58 percentage points; 95% CI, 2.31 to 10.85; P = .0026), time below range overall (adjusted mean difference, –1.34 percentage points; 95% CI, –2.19 to –0.49; P = .0020), and time below range overnight (adjusted mean difference, –1.86 percentage points; 95% CI –2.90 to –0.81; P = .0005).²

References:

1. Carlson AL, Beck RW, Li Z, et al. Glucose levels measured with continuous glucose monitoring in uncomplicated pregnancies. BMJ Open Diabetes Res Care. 2024;12(3):e003989. Published 2024 May 10. doi:10.1136/bmjdrc-2023-003989
2. Benhalima K, Beunen K, Van Wilder N, et al. Comparing advanced hybrid closed loop therapy and standard insulin therapy in pregnant women with type 1 diabetes (CRISTAL): a parallel-group, open-label, randomised controlled trial. Lancet Diabetes Endocrinol. 2024;12(6):390-403. doi:10.1016/S2213-8587(24)00089-5