Longitudinal Observation of Insulin Use and Glucose Sensor Metrics in Pregnant Women with Type 1 Diabetes Using Continuous Glucose Monitors and Insulin Pumps: The LOIS-P Study

Continuous glucose monitoring in pregnancies with type 1 diabetes: small increases in time-in-range improve maternal and perinatal outcomes

BACKGROUND

Continuous glucose monitors provide detailed information regarding glycemic control in pregnant patients with type 1 diabetes. Little data have been published examining the association between continuous glucose monitor parameters and perinatal outcomes among gravidas with type 1 diabetes using continuous glucose monitors.

OBJECTIVE

This study aimed to examine the association between perinatal outcomes and time-in-range as assessed by continuous glucose monitors used in pregnant individuals with type 1 diabetes. We hypothesized that higher time-in-range would be associated with lower risk of adverse perinatal outcomes.

STUDY DESIGN

This multicenter retrospective cohort study included all gravidas with type 1 diabetes using continuous glucose monitors who delivered from 2020 to 2022 at 5 University of California sites. Only those with continuous glucose monitor target range set to 70 to 140 mg/dL (±10 mg/dL) were included. Time-in-range (%) was recorded at 12, 16, 20, 24, 28, and 32 weeks. The primary maternal and neonatal outcomes were preeclampsia and large for gestational age, defined as birthweight ≥95th percentile. Kruskal-Wallis tests were used to compare median time-in-range between those with and without the primary outcomes. Log-binomial regression was used to obtain risk ratios, with adjustment for microvascular disease and years with type 1 diabetes.

RESULTS

A total of 91 patients were included. Most used an insulin pump (81%) and did not have diabetic microvascular disease (72%). Median time since diagnosis of type 1 diabetes was 16 years, and median periconception hemoglobin A1c was 6.7%. Compared with those with preeclampsia, normotensive gravidas had significantly higher time-in-range at nearly every time point. A similar pattern was observed for those with normal-birthweight infants compared with large-for-gestational-age infants. On adjusted analyses, every 5-unit increase in time-in-range at 12 weeks was associated with 45% and 46% reductions in the risks of preeclampsia and large for gestational age, respectively (preeclampsia: adjusted risk ratio, 0.55; 95% confidence interval, 0.30-0.99; large for gestational age: adjusted risk ratio, 0.54; 95% confidence interval, 0.29-0.99).

CONCLUSION

Higher time-in-range is associated with lower risk of preeclampsia and large for gestational age. This association is observed early in gestation, when each 5-unit increase in time-in-range is associated with ∼50% reduction in the risk of these complications. These findings can be used to counsel patients regarding the risk of pregnancy complications at specific time-in-range values, and to encourage patients that even small improvements in time-in-range can have significant impact on pregnancy outcomes. Larger studies are needed to further explore these findings and to identify optimal time-in-range to reduce perinatal complication rates.

Updates in the Management of Type 1 Diabetes in Pregnancy

The care of pregnant individuals with type 1 diabetes mellitus has experienced significant advancements in recent years. Preconception counseling has re-emerged as a core dimension of management. Continuous glucose monitoring plays an increasingly useful and beneficial role in gestational glycemic monitoring, a practice informed by improved maternofetal outcomes. While studies have not shown that continuous subcutaneous insulin infusion is superior to multiple daily injections of insulin for glycemic control, recent work has signaled that hybrid closed-loop systems with pregnancy-specific targets could meaningfully improve glycemic control and potentially ameliorate maternofetal outcomes while reducing self-care burden.

Pregnancy and delivery in an advanced cancer survivor with immune checkpoint inhibitor-induced type 1 diabetes: a case report

PURPOSE

Given the rarity and elderly onset of immune checkpoint inhibitor (ICI)-induced type 1 diabetes (ICI-T1DM), cases leading to delivery are rare.

METHOD

To our knowledge, this is the first case report of childbirth in a patient with ICI-T1DM after cancer survival. A 32-year-old woman was started on Nivolumab for metastatic parotid cancers one year after total parotidectomy.

RESULT

The patient developed ICI-T1DM after 43 cycles and started multiple daily insulin therapy and self-monitoring of blood glucose. Complete response was maintained for 2 years by nivolumab, and she finished nivolumab in 77 cycles to attempt pregnancy. During the follow-up period, she began using a sensor-augmented pump (SAP). She had undetectable serum and urinary C-peptide when she started SAP. Her HbA1c level decreased from 7.8 to 6.6% without increasing hypoglycemia in one year. The patient remained in complete response after ICI discontinuation, and embryo transfer was initiated. Pregnancy was confirmed after a second embryo transfer (21 months after ICI discontinuation). At 36 weeks and 6 days, an emergency cesarean section was performed due to the onset of preeclampsia. The baby had hypospadias and bifid scrotum but no other complications or neonatal intensive care unit admission.

CONCLUSION

Because ICI discontinuation and ICI-T1DM carry risks for the patient and child, the decision regarding pregnancy warrants careful consideration. Diabetologists should collaborate with patients and other clinical departments to develop a treatment plan for childbirth.

Continuous Glucose Monitoring Metrics for Pregnancies Complicated by Diabetes: Critical Appraisal of Current Evidence

Ascertaining the utility of continuous glucose monitoring (CGM) in pregnancy complicated by diabetes is a rapidly evolving area, as the prevalence of type 1 diabetes (T1D), type 2 diabetes (T2D), and gestational diabetes mellitus (GDM) escalates. The seminal randomized controlled trial (RCT) evaluating CGM use added to standard care in pregnancy in T1D demonstrated significant improvements in maternal glycemia and neonatal health outcomes. Current clinical guidance recommends targets for percentage time in range (TIR), time above range (TAR), and time below range (TBR) during pregnancy complicated by T1D that are widely used in clinical practice. However, the superiority of CGM over blood glucose monitoring (BGM) is still questioned in both T2D and GDM, and whether glucose targets should be different than in T1D is unknown. Questions requiring additional research include which CGM metrics are superior in predicting clinical outcomes, how should pregnancy-specific CGM targets be defined, whether CGM targets should differ according to gestational age, and if CGM metrics during pregnancy should be similar across all types of diabetes. Limiting the potential for CGM to improve pregnancy outcomes may be our inability to maintain TIR > 70% throughout gestation, a goal achieved in the minority of patients studied. Adverse pregnancy outcomes remain high in women with T1D and T2D in pregnancy despite CGM technology, and this review explores the potential reasons and questions yet to be investigated.

Automated Insulin Delivery for Pregnant Women With Type 1 Diabetes: Where do we stand?

Automated insulin delivery (AID) systems mimic an artificial pancreas via a predictive algorithm integrated with continuous glucose monitoring (CGM) and an insulin pump, thereby providing AID. Outside of pregnancy, AID has led to a paradigm shift in the management of people with type 1 diabetes (T1D), leading to improvements in glycemic control with lower risk for hypoglycemia and improved quality of life. As the use of AID in clinical practice is increasing, the number of women of reproductive age becoming pregnant while using AID is also expected to increase. The requirement for lower glucose targets than outside of pregnancy and for frequent adjustments of insulin doses during pregnancy may impact the effectiveness and safety of AID when using algorithms for non-pregnant populations with T1D. Currently, the CamAPS® FX is the only AID approved for use in pregnancy. A recent randomized controlled trial (RCT) with CamAPS® FX demonstrated a 10% increase in time in range in a pregnant population with T1D and a baseline glycated hemoglobin (HbA1c) ≥ 48 mmol/mol (6.5%). Off-label use of AID not approved for pregnancy are currently also being evaluated in ongoing RCTs. More evidence is needed on the impact of AID on maternal and neonatal outcomes. We review the current evidence on the use of AID in pregnancy and provide an overview of the completed and ongoing RCTs evaluating AID in pregnancy. In addition, we discuss the advantages and challenges of the use of current AID in pregnancy and future directions for research.

Functional analysis of daily glycemic profiles and excessive fetal growth in pregnant patients with well-controlled type 1 diabetes: Retrospective cohort

AIMS

The study objective was to compare daily glycemic profiles throughout gestation between the mothers of large-for-gestational-age (LGA) and non-LGA newborns in patients with type 1 diabetes (T1D).

METHODS

We selected 102 eligible pregnant women who were treated with sensor-augmented pumps in our single-center retrospective cohort study. We used functional data analysis to compare glycemic control across gestation.

RESULTS

Median HbA1c values in the first, second, and third trimester were 6.23 %, 5.49 %, and 5.75 % respectively. Median time-in-range (TIR) exceeded 70 % in each trimester (72.4 %, 72.5 %, and 75.9 %, respectively). From 59 % up to 77 % of women met the criteria for well-controlled T1D defined by the mean HbA1c and TIR in each trimester. Despite that, 27 % (28/102) of pregnancies were complicated by LGA. Mothers of LGA infants had significantly increased HbA1c levels and decreased TIR values in the second and third trimesters. The most significant differences in daily mean glucose values between LGA and non-LGA newborns' mothers occurred between 26 and 32 weeks of pregnancy. These discrepancies were noted in daytime glucose values rather than nocturnal and fasting glucose levels.

CONCLUSIONS

Mothers of LGA newborns present significantly worse glycemic control. Our findings may emphasize the need for more rigorous daytime glycemic control.

Automated Insulin Delivery in Women with Pregnancy Complicated by Type 1 Diabetes

BACKGROUND

Hybrid closed-loop insulin therapy has shown promise for management of type 1 diabetes during pregnancy; however, its efficacy is unclear.

METHODS

In this multicenter, controlled trial, we randomly assigned pregnant women with type 1 diabetes and a glycated hemoglobin level of at least 6.5% at nine sites in the United Kingdom to receive standard insulin therapy or hybrid closed-loop therapy, with both groups using continuous glucose monitoring. The primary outcome was the percentage of time in the pregnancy-specific target glucose range (63 to 140 mg per deciliter [3.5 to 7.8 mmol per liter]) as measured by continuous glucose monitoring from 16 weeks' gestation until delivery. Analyses were performed according to the intention-to-treat principle. Key secondary outcomes were the percentage of time spent in a hyperglycemic state (glucose level >140 mg per deciliter), overnight time in the target range, the glycated hemoglobin level, and safety events.

RESULTS

A total of 124 participants with a mean (±SD) age of 31.1±5.3 years and a mean baseline glycated hemoglobin level of 7.7±1.2% underwent randomization. The mean percentage of time that the maternal glucose level was in the target range was 68.2±10.5% in the closed-loop group and 55.6±12.5% in the standard-care group (mean adjusted difference, 10.5 percentage points; 95% confidence interval [CI], 7.0 to 14.0; P<0.001). Results for the secondary outcomes were consistent with those of the primary outcome; participants in the closed-loop group spent less time in a hyperglycemic state than those in the standard-care group (difference, -10.2 percentage points; 95% CI, -13.8 to -6.6); had more overnight time in the target range (difference, 12.3 percentage points; 95% CI, 8.3 to 16.2), and had lower glycated hemoglobin levels (difference, -0.31 percentage points; 95% CI, -0.50 to -0.12). Little time was spent in a hypoglycemic state. No unanticipated safety problems associated with the use of closed-loop therapy during pregnancy occurred (6 instances of severe hypoglycemia, vs. 5 in the standard-care group; 1 instance of diabetic ketoacidosis in each group; and 12 device-related adverse events in the closed-loop group, 7 related to closed-loop therapy).

CONCLUSIONS

Hybrid closed-loop therapy significantly improved maternal glycemic control during pregnancy complicated by type 1 diabetes. (Funded by the Efficacy and Mechanism Evaluation Program; AiDAPT ISRCTN Registry number, ISRCTN56898625.).

Management of type 1 diabetes in pregnancy: update on lifestyle, pharmacological treatment, and novel technologies for achieving glycaemic targets

Glucose concentrations within target, appropriate gestational weight gain, adequate lifestyle, and, if necessary, antihypertensive treatment and low-dose aspirin reduces the risk of pre-eclampsia, preterm delivery, and other adverse pregnancy and neonatal outcomes in pregnancies complicated by type 1 diabetes. Despite the increasing use of diabetes technology (ie, continuous glucose monitoring and insulin pumps), the target of more than 70% time in range in pregnancy (TIRp 3·5-7·8 mmol/L) is often reached only in the final weeks of pregnancy, which is too late for beneficial effects on pregnancy outcomes. Hybrid closed-loop (HCL) insulin delivery systems are emerging as promising treatment options in pregnancy. In this Review, we discuss the latest evidence on pre-pregnancy care, management of diabetes-related complications, lifestyle recommendations, gestational weight gain, antihypertensive treatment, aspirin prophylaxis, and the use of novel technologies for achieving and maintaining glycaemic targets during pregnancy in women with type 1 diabetes. In addition, the importance of effective clinical and psychosocial support for pregnant women with type 1 diabetes is also highlighted. We also discuss the contemporary studies examining HCL systems in type 1 diabetes during pregnancies.

Epidemiology and Therapeutic Strategies for Women With Preexisting Diabetes in Pregnancy: How Far Have We Come? The 2021 Norbert Freinkel Award Lecture

The field of diabetes in pregnancy has witnessed tremendous changes over the past 30 years, with an explosive growth in case numbers along with new and exciting opportunities to affect outcomes. Type 1 diabetes in pregnancy has increased by 40%, but type 2 diabetes in pregnancy, rarely seen 30 years ago, has more than doubled and, in some cases, tripled in prevalence. Compared with women with type 2 diabetes, women with type 1 diabetes have higher HbA1c, more large-for-gestational-age infants, and more preterm births. Women with type 2 diabetes have more chronic hypertension, more socioeconomic deprivation, and higher rates of perinatal mortality. Large randomized trials in women with diabetes in pregnancy have helped us understand the effectiveness of new technologies (i.e., continuous glucose monitoring) in women with type 1 diabetes, and the addition of metformin to insulin in women with type 2 diabetes, in improving pregnancy outcomes. Future endeavors, including artificial pancreas systems in women with type 1 diabetes and the use of continuous glucose monitoring, a better understanding of nutrition during pregnancy, and approaches to improve preconception and pregnancy self-care in women with type 2 diabetes, may lead to further improved outcomes.

Hypoglycemia in Prospective Multicenter Study of Pregnancies with Pre-Existing Type 1 Diabetes on Sensor-Augmented Pump Therapy: The LOIS-P Study

Background: Pregnancies in type 1 diabetes are high risk, and data in the United States are limited regarding continuous glucose monitoring (CGM)-based hypoglycemia throughout pregnancy while on sensor-augmented insulin pump therapy. Materials and Methods: Pregnant women with type 1 diabetes in the LOIS-P Study (Longitudinal Observation of Insulin use and glucose Sensor metrics in Pregnant women with type 1 diabetes using continuous glucose monitors and insulin pumps) were enrolled before 17 weeks gestation at three U.S. centers and we used their personal insulin pump and a study Dexcom G6 CGM. We analyzed data of 25 pregnant women for CGM hypoglycemia based on international consensus guidelines for percentage time <63 and 54 mg/dL, hypoglycemic events and prolonged hypoglycemia events for 24-h, daytime, and overnight periods, and severe hypoglycemia (SH) episodes. Results: For a 24-h period, biweekly median percentage of time <63 mg/dL ranged from 0.8% at biweek 4-5 to 3.7% at biweek 14-15 with high variability throughout pregnancy. Median percentage of time <63 and 54 mg/dL was higher overnight than daytime (P < 0.01). Hypoglycemic events occurred throughout the pregnancy, ranged 1-4 events per 2 weeks, significantly decreased after the 20th week, and occurred predominantly during daytime (P < 0.01). For overnight period, hypoglycemia and events were more concentrated from 12 to 3 am. Seven prolonged hypoglycemia events without any associated SH occurred in four participants (16%), primarily overnight. Three participants experienced a single episode of SH. Conclusions: Our results suggest a higher overall risk of hypoglycemia throughout pregnancy during the overnight period with continued daytime risk of hypoglycemic events in pregnancies complicated by type 1 diabetes.

Continuous Glucose Monitoring Metrics and Birth Weight: Informing Management of Type 1 Diabetes Throughout Pregnancy

OBJECTIVE

To determine gestational weekly changes in continuous glucose monitoring (CGM) metrics and 24-h glucose profiles and their relationship to infant birth weight in pregnant women with type 1 diabetes.

RESEARCH DESIGN AND METHODS

An analysis of >10.5 million CGM glucose measures from 386 pregnant women with type 1 diabetes from two international multicenter studies was performed. CGM glucose metrics and 24-h glucose profiles were calculated for each gestational week, and the relationship to normal (10-90th percentile) and large (>90th percentile) for gestational age (LGA) birth weight infants was determined.

RESULTS

Mean CGM glucose concentration fell and percentage of time spent in the pregnancy target range of 3.5-7.8 mmol/L (63-140 mg/dL) increased in the first 10 weeks of pregnancy and plateaued until 28 weeks of gestation, before further improvement in mean glucose and percentage of time in range until delivery. Maternal CGM glucose metrics diverged at 10 weeks of gestation, with significantly lower mean CGM glucose concentration (7.1 mmol/L; 95% CI 7.05-7.15 [127.8 mg/dL; 95% CI 126.9-128.7] vs. 7.5 mmol/L; 95% CI 7.45-7.55 [135 mg/dL; 95% CI 134.1-135.9]) and higher percentage of time in range (55%; 95% CI 54-56 vs. 50%; 95% CI 49-51) in women who had normal versus LGA. The 24-h glucose profiles were significantly higher across the day from 10 weeks of gestation in LGA.

CONCLUSIONS

Normal birth weight is associated with achieving significantly lower mean CGM glucose concentration across the 24-h day and higher CGM time in range from before the end of the first trimester, emphasizing the need for a shift in clinical management, with increased focus on using weekly CGM glucose targets for optimizing maternal glycemia from early pregnancy.

Feasibility of Closed-Loop Insulin Delivery with a Pregnancy-Specific Zone Model Predictive Control Algorithm

Objective: Evaluating the feasibility of closed-loop insulin delivery with a zone model predictive control (zone-MPC) algorithm designed for pregnancy complicated by type 1 diabetes (T1D). Research Design and Methods: Pregnant women with T1D from 14 to 32 weeks gestation already using continuous glucose monitor (CGM) augmented pump therapy were enrolled in a 2-day multicenter supervised outpatient study evaluating pregnancy-specific zone-MPC based closed-loop control (CLC) with the interoperable artificial pancreas system (iAPS) running on an unlocked smartphone. Meals and activities were unrestricted. The primary outcome was the CGM percentage of time between 63 and 140 mg/dL compared with participants' 1-week run-in period. Early (2-h) postprandial glucose control was also evaluated. Results: Eleven participants completed the study (age: 30.6 ± 4.1 years; gestational age: 20.7 ± 3.5 weeks; weight: 76.5 ± 15.3 kg; hemoglobin A1c: 5.6% ± 0.5% at enrollment). No serious adverse events occurred. Compared with the 1-week run-in, there was an increased percentage of time in 63-140 mg/dL during supervised CLC (CLC: 81.5%, run-in: 64%, P = 0.007) with less time >140 mg/dL (CLC: 16.5%, run-in: 30.8%, P = 0.029) and time <63 mg/dL (CLC: 2.0%, run-in:5.2%, P = 0.039). There was also less time <54 mg/dL (CLC: 0.7%, run-in:1.6%, P = 0.030) and >180 mg/dL (CLC: 4.9%, run-in: 13.1%, P = 0.032). Overnight glucose control was comparable, except for less time >250 mg/dL (CLC: 0%, run-in:3.9%, P = 0.030) and lower glucose standard deviation (CLC: 23.8 mg/dL, run-in:42.8 mg/dL, P = 0.007) during CLC. Conclusion: In this pilot study, use of the pregnancy-specific zone-MPC was feasible in pregnant women with T1D. Although the duration of our study was short and the number of participants was small, our findings add to the limited data available on the use of CLC systems during pregnancy (NCT04492566).

AiDAPT: automated insulin delivery amongst pregnant women with type 1 diabetes: a multicentre randomized controlled trial - study protocol

Background

Pregnant women with type 1 diabetes strive for tight glucose targets (3.5-7.8 mmol/L) to minimise the risks of obstetric and neonatal complications. Despite using diabetes technologies including continuous glucose monitoring (CGM), insulin pumps and contemporary insulin analogues, most women struggle to achieve and maintain the recommended pregnancy glucose targets. This study aims to evaluate whether the use of automated closed-loop insulin delivery improves antenatal glucose levels in pregnant women with type 1 diabetes.

Methods/design

A multicentre, open label, randomized, controlled trial of pregnant women with type 1 diabetes and a HbA1c of ≥48 mmol/mol (6.5%) at pregnancy confirmation and ≤ 86 mmol/mol (10%) at randomization. Participants who provide written informed consent before 13 weeks 6 days gestation will be entered into a run-in phase to collect 96 h (24 h overnight) of CGM glucose values. Eligible participants will be randomized on a 1:1 basis to CGM (Dexcom G6) with usual insulin delivery (control) or closed-loop (intervention). The closed-loop system includes a model predictive control algorithm (CamAPS FX application), hosted on an android smartphone that communicates wirelessly with the insulin pump (Dana Diabecare RS) and CGM transmitter. Research visits and device training will be provided virtually or face-to-face in conjunction with 4-weekly antenatal clinic visits where possible. Randomization will stratify for clinic site. One hundred twenty-four participants will be recruited. This takes into account 10% attrition and 10% who experience miscarriage or pregnancy loss. Analyses will be performed according to intention to treat. The primary analysis will evaluate the change in the time spent in the target glucose range (3.5-7.8 mmol/l) between the intervention and control group from 16 weeks gestation until delivery. Secondary outcomes include overnight time in target, time above target (> 7.8 mmol/l), standard CGM metrics, HbA1c and psychosocial functioning and health economic measures. Safety outcomes include the number and severity of ketoacidosis, severe hypoglycaemia and adverse device events.

Discussion

This will be the largest randomized controlled trial to evaluate the impact of closed-loop insulin delivery during type 1 diabetes pregnancy.

Trial registration

ISRCTN 56898625 Registration Date: 10 April, 2018.

Time in range measurements for hyperglycemia management during pregnancy

The prevalence of adverse pregnancy outcomes associated with poor glycemic control are increasing. Accordingly, effective blood glucose monitoring during pregnancy has become a subject of intense interest. Continuous glucose monitoring (CGM) displays dynamic changes in blood glucose by using probes to measure glucose concentration in the interstitial fluid, and the rapid development of CGM has enabled the investigation of time in range (TIR) in the glucose target range as a new parameter to evaluate blood glucose. International guidelines have identified TIR as an important blood glucose assessment method for pregnant patients with type 1 diabetes mellitus that overcomes the limitations of conventional gestational blood glucose monitoring, better reflects fluctuation in blood glucose during pregnancy, and effectively improves maternal and neonatal outcomes. However, there is little clinical evidence for the use of TIR in pregnant women with gestational diabetes mellitus and those with pre-pregnant type 2 diabetes mellitus. TIR is expected to become a critical indicator of blood glucose control and management in hyperglycemic pregnant patients. We review the research progress of TIR to help clinicians understand the field of blood glucose monitoring in pregnant women with hyperglycemia.

Zone-MPC Automated Insulin Delivery Algorithm Tuned for Pregnancy Complicated by Type 1 Diabetes

Type 1 diabetes (T1D) increases the risk for pregnancy complications. Increased time in the pregnancy glucose target range (63-140 mg/dL as suggested by clinical guidelines) is associated with improved pregnancy outcomes that underscores the need for tight glycemic control. While closed-loop control is highly effective in regulating blood glucose levels in individuals with T1D, its use during pregnancy requires adjustments to meet the tight glycemic control and changing insulin requirements with advancing gestation. In this paper, we tailor a zone model predictive controller (zone-MPC), an optimization-based control strategy that uses model predictions, for use during pregnancy and verify its robustness in-silico through a broad range of scenarios. We customize the existing zone-MPC to satisfy pregnancy-specific glucose control objectives by having (i) lower target glycemic zones (i.e., 80-110 mg/dL daytime and 80-100 mg/dL overnight), (ii) more assertive correction bolus for hyperglycemia, and (iii) a control strategy that results in more aggressive postprandial insulin delivery to keep glucose within the target zone. The emphasis is on leveraging the flexible design of zone-MPC to obtain a controller that satisfies glycemic outcomes recommended for pregnancy based on clinical insight. To verify this pregnancy-specific zone-MPC design, we use the UVA/Padova simulator and conduct in-silico experiments on 10 subjects over 13 scenarios ranging from scenarios with ideal metabolic and treatment parameters for pregnancy to extreme scenarios with such parameters that are highly deviant from the ideal. All scenarios had three meals per day and each meal had 40 grams of carbohydrates. Across 13 scenarios, pregnancy-specific zone-MPC led to a 10.3 ± 5.3% increase in the time in pregnancy target range (baseline zone-MPC: 70.6 ± 15.0%, pregnancy-specific zone-MPC: 80.8 ± 11.3%, p < 0.001) and a 10.7 ± 4.8% reduction in the time above the target range (baseline zone-MPC: 29.0 ± 15.4%, pregnancy-specific zone-MPC: 18.3 ± 12.0, p < 0.001). There was no significant difference in the time below range between the controllers (baseline zone-MPC: 0.5 ± 1.2%, pregnancy-specific zone-MPC: 3.5 ± 1.9%, p = 0.1). The extensive simulation results show improved performance in the pregnancy target range with pregnancy-specific zone MPC, suggest robustness of the zone-MPC in tight glucose control scenarios, and emphasize the need for customized glucose control systems for pregnancy.

Assessing Glycemic Control Using CGM for Women with Diabetes in Pregnancy

PURPOSE OF REVIEW

Diabetes during pregnancy increases the risk of maternal and fetal complications. This article reviews the types of CGM currently available, the glucose metrics which correlate with pregnancy outcomes, endocrine organization recommendations, clinical considerations for CGM implementation, and anticipated directions for future research.

RECENT FINDINGS

CGM use during pregnancy is increasing, and recommendations for use have been incorporated into many organizations' consensus guidelines. Increased time spent within a target range of 63-140 mg/dL and lower mean glucose are associated with lower risk of neonatal complications including large for gestational age infants. Use of CGM during pregnancy can detect postprandial and nocturnal hyperglycemia missed by self-monitoring of blood glucose (SMBG) which can be used for prognosis and to guide pharmacologic interventions. The use of continuous glucose monitoring (CGM) during pregnancies complicated by type 1, type 2, and gestational diabetes has been shown to improve outcomes.