A Study of the Carbohydrate-to-Insulin Ratio in Pregnant Women with Type 1 Diabetes on Pump Treatment

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.

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

Background: Suboptimal glycemic control is associated with maternal and neonatal morbidity and mortality in pregnancy complicated by type 1 diabetes (T1D). Prospective analysis of continuous glucose monitoring (CGM) metrics, insulin pump settings, and insulin delivery can better characterize the changes in glycemic levels and insulin use throughout pregnancy with T1D. Materials and Methods: Prescribed parameters, insulin delivery, carbohydrate intake, and CGM data for 25 pregnant women with T1D from three U.S. sites were collected. Participants enrolled before 17 weeks gestation and used personal insulin pumps and study CGM. Mean daily total, basal, and bolus insulin doses (units/kg), CGM time in range (TIR: 63-140 mg/dL), and pump-entered carbohydrates were analyzed for every 2-week gestational interval. Linear mixed-effects regression models were used to evaluate changes across gestational ages compared to 12-14 weeks. Results: Basal insulin was higher during weeks 6-12 and 24-40. Daily bolus and total insulin were higher during weeks 20-40. Pump parameters were adjusted to intensify insulin therapy from 22 weeks onward. Average TIR across pregnancy was 59% ± 14%. Between 18 and 30 weeks, TIR was significantly lower, and time above range was significantly higher compared to the reference biweek. Time below target was lower between 22 and 34 weeks. Seven participants achieved >70% recommended TIR for pregnancy. Participants with maternal complications or infant neonatal intensive care unit admissions had lower TIR. Conclusion: While insulin dosing changed significantly with advancing gestation, most participants did not achieve >70% TIR. Customized anticipatory pump setting adjustments and automated systems aimed toward the designated TIR are needed to improve outcomes for this population. NCT03761615.

CopenFast trial: Faster-acting insulin Fiasp versus insulin NovoRapid in the treatment of women with type 1 or type 2 diabetes during pregnancy and lactation - a randomised controlled trial

INTRODUCTION

Faster-acting insulin aspart (Fiasp) is approved for use in pregnancy and lactation, but no clinical study has evaluated its effects during this life stage in women with pre-existing diabetes. The aim of the CopenFast trial is to evaluate the effect of Fiasp compared with insulin aspart (NovoRapid) on maternal glycaemic control during pregnancy, delivery and lactation and on fetal growth and infant health.

METHODS AND ANALYSIS

An open-label randomised controlled trial of pregnant women with type 1 or type 2 diabetes including women on multiple daily injection (MDI) therapy or insulin pump therapy. During a 2-year inclusion period, approximately 220 women will be randomised 1:1 to Fiasp or NovoRapid in early pregnancy and followed until 3 months after delivery. At 9, 21 and 33 gestational weeks and during planned induction of labour or caesarean section, women are offered blinded continuous glucose monitoring (CGM) for 7 days. Randomisation will stratify for type of diabetes and insulin treatment modality (MDI or insulin pump therapy, respectively). Health status of the infants will be followed until 3 months of age. The primary outcome is birth weight SD score adjusted for gestational age and gender. Secondary outcomes include maternal glycaemic control including glycated haemoglobin, preprandial and postprandial self-monitored plasma glucose levels, episodes of mild and severe hypoglycaemia, maternal gestational weight gain and weight retention, CGM time spent in, above and below target ranges as well as pregnancy outcomes including pre-eclampsia, preterm delivery, perinatal mortality and neonatal morbidity. Data analysis will be performed according to the intention-to-treat principle.

ETHICS AND DISSEMINATION

The trial has been approved by the Regional Ethics Committee (H-19029966) on 7 August 2019. Results will be sought disseminated in peer-reviewed journals and at scientific meetings.

TRIAL REGISTRATION NUMBER

NCT03770767.

Insulin Requirements and Carbohydrate to Insulin Ratio in Normal Weight, Overweight, and Obese Women With Type 1 Diabetes Under Pump Treatment During Pregnancy: A Lesson From Old Technologies

AIM

The primary aim of this study was to assess insulin requirements and carbohydrate to insulin ratio (CHO/IR) in normal weight, overweight, and obese pregnant women with type 1 diabetes across early, middle, and late pregnancy.

METHODS

In this multicenter, retrospective, observational study we evaluated 86 of 101 pregnant Caucasian women with type 1 diabetes under pump treatment. The women were trained to calculate CHO/IR daily by dividing CHO grams of every single meal by insulin units injected. Since the purpose of the study was to identify the CHO/IR able to reach the glycemic target, we only selected the CHO/IR obtained when glycemic values were at target. Statistics: SPSS 20.

RESULTS

We studied 45 normal weight, 31 overweight, and 10 obese women. Insulin requirements increased throughout pregnancy (p < 0.0001 and <0.001 respectively) in the normal and overweight women, while it remained unchanged in the obese women. Insulin requirements were different between groups when expressed as an absolute value, but not when adjusted for body weight. Breakfast CHO/IR decreased progressively throughout pregnancy in the normal weight women, from 13.3 (9.8-6.7) at the first stage of pregnancy to 6.2 (3.8-8.6) (p = 0.01) at the end stage, and in the overweight women from 8.5 (7.1-12.6) to 5.2 (4.0-8.1) (p = 0.001), while in the obese women it remained stable, moving from 6.0 (5.0-7.9) to 5.1 (4.1-7.4) (p = 0.7). Likewise, lunch and dinner CHO/IR decreased in the normal weight and overweight women (p < 0.03) and not in the obese women. The obese women gained less weight than the others, especially in early pregnancy when they even lost a median of 1.25 (-1 -1.1) kg (p = 0.005). In early pregnancy, we found a correlation between pregestational BMI and insulin requirements (IU/day) or CHO/IR at each meal (p < 0.001 and p = 0.001, respectively). In late pregnancy, a relationship between pre-gestational BMI and CHO/IR change was found (P = 0.004), as well as between weight gain and CHO/IR change (p=0.02). The significance was lost when both variables were included in the multiple regression analysis. There was no difference in pregnancy outcomes except for a higher pre-term delivery rate in the obese women.

CONCLUSION

Pre-gestational BMI and weight gain may play a role in determining CHO/IR during pregnancy in women with type 1 diabetes under pump treatment.

Performance of the Dexcom G6 Continuous Glucose Monitoring System in Pregnant Women with Diabetes

Background: The aim of this study was to determine the performance of the Dexcom G6 continuous glucose monitoring (CGM) system across three sensor wear sites in pregnant women with diabetes in the second or third trimesters. Methods: Participants with type 1 (T1D), type 2 (T2D), or gestational (GDM) diabetes mellitus were enrolled at three sites. Each wore two G6 sensors on the abdomen, upper buttock, and/or posterior upper arm for 10 days and underwent a 6-h clinic session between days 3 and 7 of sensor wear, during which YSI reference blood glucose values were obtained every 30 min. No intentional glucose manipulations were performed. Accuracy metrics included the proportion of CGM values that were within ±20% of paired reference values >100 mg/dL or ±20 mg/dL of YSI values ≤100 mg/dL (hereafter referred to as %20/20), as well as the analogous %15/15, %30/30, and %40/40. The mean absolute relative difference (MARD) between CGM-YSI pairs was also calculated. Results: Thirty-two participants with T1D (n = 20), T2D (n = 3), or GDM (n = 9) were enrolled: 19 were in the second trimester and 13 were in the third trimester of pregnancy. Compared with the reference, 92.5% of CGM values were within ±20%/20 mg/dL. The overall MARD and that of sensors worn on the abdomen, upper buttock, and posterior upper arm was 10.3%, 11.5%, 11.2%, and 8.7%, respectively. There were no device-related adverse events. Skin reactions at the insertion sites were absent or minor. Conclusions: The Dexcom G6 CGM system is accurate and safe in pregnant women with diabetes.

Insulin Therapy and Diabetic Pregnancy

BACKGROUND

A good metabolic control before conception and throughout pregnancy with diabetes decreases the risk of short- and long-term adverse outcomes of the mothers and their offsprings. Insulin treatment remains the gold standard treatment recommended for any type of diabetes. New technologies including new insulins and insulin analogues, continuous subcutaneous insulin infusion without and with sensors, the low-glucose predictive suspension function, and closed-loop systems that persistently and automatically self-adjust according to patients' continuous glucose monitoring readings have expanded the offer to clinicians for achieving tight glucose control.

AREAS OF UNCERTAINTY

Unsafe effects of insulin and insulin analogues in pregnancy with diabetes could be linked with changes in insulin immunogenicity, teratogenicity, and mitogenicity. Second-generation insulin analogues need to be tested and proven. Effectiveness and safety of new insulin delivery systems in real life of diabetic women in pregnancy need further confirmations.

SOURCES

MEDLINE, EMBASE, Web of Science, Cochrane Library, randomized controlled trials, systematic review and meta-analysis, observational prospective and retrospective studies, case series reports for the most recent insulin analogues, published in English impacted journals, and consensus statements from scientific societies I excluded 60 from 221 papers as not suitable for the purpose of the subject.

RESULTS

Subcutaneous insulin infusion can be safely used during pregnancy and delivery of well-trained women. Sensors are increasingly accurate tools that improve the efficacy and safety of integrated systems' functioning. Continuous glucose monitoring provides metrics ("time in range" time in "hypoglycemia" and in "hyperglycemia," glucose variability, average glucose levels in different time intervals) used as a guide to diabetes management; these new metrics are object of discussion in special populations. Randomized controlled trials have shown that sensor-augmented pump therapy improves pregnancy outcomes in women with type 1 diabetes. Closed-loop insulin delivery provides better glycemic control than sensor-augmented pump therapy during pregnancy, before, and after delivery.

CONCLUSION

Second-generation insulin analogues and newer insulin infusion systems that automatically self-adjust according to patients continuous glucose monitor readings are important tools improving the treatment and quality of life of these women. Multi-institutional and disciplinary teams are working to develop and evaluate a pregnancy-specific artificial pancreas.

Pregnancy Outcomes and Insulin Requirements in Women with Type 1 Diabetes Treated with Continuous Subcutaneous Insulin Infusion and Multiple Daily Injections: Cohort Study

BACKGROUND

We aimed to compare glycemic control, insulin requirements, and outcomes in women with type 1 diabetes in pregnancy treated with continuous subcutaneous insulin infusion (CSII) and multiple daily injections (MDI).

METHODS

A retrospective cohort study was conducted of singleton pregnancies (>20 weeks gestation) in women with type 1 diabetes (2010-2015) at a specialist multidisciplinary maternity network in Australia. Antenatal characteristics, diabetes history and treatment details, and maternal and neonatal outcomes were compared for women with type 1 diabetes using CSII and MDI. Bolus calculator settings were reviewed for CSII. Data were obtained from individual medical records, linkage to pathology, and the Birthing Outcomes System database.

RESULTS

There were no differences in maternal characteristics or diabetes history between women managed with CSII (n = 40) and MDI (n = 127). Women treated with CSII required less insulin and less increase in total daily insulin dose/kg than MDI (40% vs. 52%). Both groups achieved similar glycemic control and no differences in pregnancy outcome. In the CSII group, carbohydrate:insulin ratios were intensified across gestation (30% breakfast, 27% lunch, 22% dinner), and insulin sensitivity factors (ISFs) changed little (7% breakfast, 0% lunch, -10% dinner).

CONCLUSIONS

There was no difference in glycemic control or pregnancy outcomes in women using CSII or MDI managed in a multidisciplinary setting. Greater adjustments are needed to ISFs with CSII therapy. Overall, these data do not support recommending CSII in pregnancy with potentially higher patient and staff demands and costs and lack of improvement in HbA1c and pregnancy outcomes.