Managing Blood Glucose Levels for Expectant Mothers With Diabetes

Continuous glucose monitoring (CGM) has emerged as a revolutionary tool in the management of diabetes, particularly beneficial for pregnant women. CGM systems utilize a wearable sensor that continuously tracks glucose levels in the interstitial fluid, providing real-time data and trends on a patient’s glucose levels throughout the day. This continuous stream of information allows for more nuanced adjustments to insulin therapy and dietary management compared with traditional blood glucose monitoring methods that offer only snapshot readings.

The importance of maintaining strict glucose control during pregnancy cannot be overstated. Proper glycemic control is crucial for minimizing the risk of pregnancy complications such as preeclampsia, cesarean delivery, and macrosomia (large birth weight babies), as well as long-term health issues for the child, including an increased risk for obesity and diabetes. Metrics like hemoglobin A_1c (HbA_1c) and blood glucose levels have been the cornerstone of diabetes management. However, achieving and maintaining target glycemic control is especially vital during pregnancy. Hyperglycemia, or high blood glucose, can lead to adverse outcomes for mother and baby, making a reliable and effective glucose monitoring system an essential component of diabetes care in pregnancy.¹

Despite the clear advantages of CGM in providing comprehensive glucose data, there have been reservations about its accuracy and utility specifically in the pregnant population. The concerns stem from the need for more conclusive data on the use of CGM in pregnancy and the potential for variability in sensor accuracy. Nonetheless, the principle behind CGM use—offering a more detailed picture of glucose levels throughout the day—presents a compelling case for its integration into the management plan for expectant mothers with diabetes. As CGM technology continues to advance and more research becomes available, its role in optimizing glycemic control during pregnancy is likely to become increasingly indispensable, ensuring healthier outcomes for mothers and their babies.

CGM in Pregnancy: Benefits and Considerations

The advent of CGM systems marks a significant advancement in the management of diabetes, particularly for pregnant women. Unlike traditional self-monitoring blood glucose (SMBG) methods, which rely on intermittent finger-stick tests, CGM provides a more comprehensive picture of glucose levels throughout the day by measuring interstitial glucose levels. The Table highlights key characteristics of different glucose monitoring methods.^2,3 This measurement, albeit slightly delayed (5-15 minutes behind blood glucose levels), offers up to 288 readings per day, enabling detailed monitoring of glucose fluctuations that SMBG cannot match.

The CONCEPTT trial (NCT01788527) in 2017 was a pivotal moment in the research on CGM use during pregnancy. It demonstrated that pregnant women with type 1 diabetes using CGM had mildly improved HbA_1c levels, spent more time within the target glucose range, and experienced fewer hypoglycemic events compared with those using SMBG.⁴ Notably, the trial also revealed significant benefits for neonatal health outcomes, including reduced incidences of large gestational age births, neonatal intensive care unit (NICU) admissions, neonatal hypoglycemia, and shorter hospital stays. These findings underscore the potential of CGM to not only optimize maternal glycemic control but also enhance neonatal health outcomes.⁴

Recent research has emphasized the importance of the time in range (TIR) metric, which measures the duration a patient’s glucose levels within a target range (63-140 mg/dL).⁵ Studies have consistently shown a strong correlation between higher TIR and improved pregnancy-associated health outcomes, such as reduced risks of large gestational age births, gestational hypertension, and NICU admissions.^6-8

The American Diabetes Association has updated its standards of care to recommend CGM use in pregnancies complicated by type 1 diabetes, citing limited but promising data for those with type 2 or gestational diabetes. Although recommendations for CGM use in type 2 diabetes and gestational diabetes during pregnancy are still evolving, emerging research suggests similar benefits across these groups.⁵

Implementing CGM in a Diabetes Management Plan

Incorporating CGM into a diabetes management plan during pregnancy requires careful consideration of its benefits and limitations. Although CGM reduces the need for frequent finger-stick glucose tests, calibration with SMBG is necessary to ensure accuracy. Despite this, the comprehensive data provided by CGM can significantly enhance glycemic control strategies. It allows for real-time monitoring of glucose levels, facilitating immediate adjustments in insulin dosing and dietary management. By tracking glucose levels overnight and after meals, CGM enables a more tailored approach to managing diabetes, aiming to minimize hyperglycemia and prevent hypoglycemia.

Pharmacists play a crucial role in integrating CGM into the diabetes care plan for patients who are pregnant. Pharmacists should evaluate each patient’s specific needs, preferences, and risk factors to determine the most appropriate use of CGM. Education on the use, interpretation, and limitations of CGM data is essential for empowering patients to actively participate in their care.

As research continues to evolve, the evidence supporting the use of CGM in pregnancy is becoming increasingly compelling. It offers a promising avenue for improving maternal and neonatal outcomes by enabling more precise and individualized management of diabetes. With further study and technological advancements, CGM has the potential to become a standard component of care for all pregnant women with diabetes, ensuring healthier pregnancies and improved outcomes for both mothers and their babies.

References

1. Klonoff DC, Ahn D, Drincic A. Continuous glucose monitoring: a review of the technology and clinical use. Diabetes Res Clin Pract. 2017;133:178-192. doi:10.1016/j.diabres.2017.08.005

2. Kalra S, Gupta Y. Ambulatory glucose profile: flash glucose monitoring. J Pak Med Assoc. 2015;65(12):1360-1362.

3. Heinemann L, Freckmann G. CGM versus FGM; or, continuous glucose monitoring is not flash glucose monitoring. J Diabetes Sci Technol. 2015;9(5):947-950. doi:10.1177/1932296815603528

4. Feig DS, Donovan LE, Corcoy R, et al; CONCEPTT Collaborative Group. Continuous glucose monitoring in pregnant women with type 1 diabetes (CONCEPTT): a multicentre international randomised controlled trial. Lancet. 2017;390(10110):2347-2359. doi:10.1016/S0140-6736(17)32400-5

5. ElSayed NA, Aleppo G, Aroda VR, et al. 15. Management of diabetes in pregnancy: Standards of Care in Diabetes—2023. Diabetes Care. 2023;46(suppl 1):S254-S266. doi:10.2337/dc23-S015

6. Lai M, Weng J, Yang J, et al. Effect of continuous glucose monitoring compared with self-monitoring of blood glucose in gestational diabetes patients with HbA1c<6%: a randomized controlled trial. Front Endocrinol (Lausanne). 2023;14:1174239. doi:10.3389/fendo.2023.1174239

7. Bitar G, Cornthwaite JA, Sadek S, et al. Continuous glucose monitoring and time in range: association with adverse outcomes among people with type 2 or gestational diabetes mellitus. Am J Perinatol. Published online March 1, 2023. doi:10.1055/s-0043-1764208

8. García-Moreno RM, Benítez-Valderrama P, Barquiel B, et al. Efficacy of continuous glucose monitoring on maternal and neonatal outcomes in gestational diabetes mellitus: a systematic review and meta-analysis of randomized clinical trials. Diabet Med. 2022;39(1):e14703. doi:10.1111/dme.14703