Getting pregnant when you have type 1 diabetes carries a risk of complications, like congenital anomalies, preterm birth and miscarriage.

Additionaly, over 50% of babies born to women with type 1 diabetes are large-for-gestational-age (NIDP), and 25% experience neonatal hypoglycemia, requiring admission to the NICU.

 

That's why woman with type 1 diabetes need to aim for very strict glucose targets:

• an HbA1c ≤ 6.5% (48 mmol/mol) in early pregnancy
• and an HbA1c level < 6.0% (42 mmol/mol) during pregnancy.

 

However, achieving these targets is extremely challenging, with only a minority of pregnant women with type 1 diabetes succeeding.

• In 2020, only 17.5% of British pregnant women with type 1 diabetes achieved an HbA1c level of ≤ 6.5% (48 mmol/mol) in early pregnancy
• and 23% achieved an HbA1c level of < 6.1% (43 mmol/mol) in late pregnancy (NIDP).

 

On top of that, pregnant women with type 1 diabetes have a very high risk of severe hypoglycemia and ketoacidosis.

• In 2019, 14% of British pregnant women with type 1 diabetes were hospitalized for hypoglycemia
• and 3.2% for ketoacidosis (NIDP).

 

An increasing number of people with type 1 diabetes are turning to closed-loop systems to simplify glucose control during pregnancy and childbirth.

 

However, since there is only one approved closed-loop system with limited availability (CamAPS FX is only accessible in select European countries), the majority of pregnant women with type 1 diabetes use off-label closed-loop systems.

 

Last month, several interesting articles were published on the use of closed-loop systems during pregnancy.

• These include both general guidelines (Szmuilowicz et al. DTT 2023),
• the study design with the MiniMed 780G (Beunen et al. BMC Pregnancy and Childbirth 2023),
• some case reports with Tandem Control IQ (Wang et al. Diabetic Medicine 2023)
• and healthcare providers' experiences in the study with CamAPS FX in pregnant women (Rankin et al. DTT 2023).

 

In this article, we will discuss

• guidelines for the necessary glycemic control and use of diabetes technology during pregnancy,
• general and device-specific tips for the use of closed-loop systems during pregnancy,
• and an update on a new pregnancy-specific closed-loop system that was presented at the ATTD.

  

 

 #1 How strict should glycemic control be in pregnant women with type 1 diabetes?

"The group reached consensus on glycemic cutpoints (a target range of 63–140 mg/dL [3.5–7.8 mmol/L] during pregnancy, along with a set of targets for the time per day [% of CGM readings or minutes/hours]) women during pregnancy should strive to achieve. It should be noted that premeal and postprandial SMBG targets remain for diabetes in pregnancy, in addition to the new CGM TIR targets for overall glycemia." - Battelino et al. Diabetes care 2019

 

Before Pregnany

Both the UK NICE and the US ADA Standards of Medical Care 2023 guidelines recommend aiming for an HbA1c of ≤ 6.5% (48 mmol/l) before pregnancy to prevent pregnancy complications.

Even in 2020, there is still a clear association between an HbA1c of > 6.5% (48 mmol/mol) and the rate of congenital anomalies/miscarriages in pregnant women with diabetes. (see figure from NIDP)

 

During pregnancy

During pregnancy, women with type 1 diabetes are advised to aim for

• a time in range (TIR) of 63-140 mg/dl (3.5-7.8 mmol/) > 70%,
• a time below range (TBR) of <63 mg/dl (3.5 mmol/l) < 4%,
• a fasting glycemia of 70-95 mg/dl (3.9-5.3 mmol/l),
• a glycemia of 110-140 mg/dl (6.1-7.8 mmol/l) 1 hour after meals,
• a glycemia of 100-120 mg/dl (5.6-6.7 mmol/l) 2 hours after meals,
• and an HbA1c of < 6% (42 mmol/mol), which can be relaxed to < 7% (53 mmol/l) if necessary to avoid hypoglycemia.

 

Keep in mind that HbA1c is not the most reliable indicator for assessing glycemic control during pregnancy, as it tends to be lower since red blood cell turnover increases in expectant mothers.

Furthermore, towards the end of pregnancy, some women may experience higher HbA1c levels which may also be attributed to ferric anemia.

 

During and after childbirth

It is important to note that determining the ideal glycemic target during labor, delivery, and soon after remains a challenge and is not yet fully understood.

While it was once believed to be crucial in preventing neonatal hypoglycemia, recent evidence has contradicted this assumption.

There is increasing evidence that glycaemic control in the second and third trimester of pregnancy, contribute more to the risk of neonatal hypoglycaemia.

 

Recent British guidelines offer 2 approaches:

• the traditional approach with tight glycaemic targets (72-126 mg/dl or 4.0–7.0 mmol/l)
• and an updated pragmatic approach (90-144 mg/dl or 5.0–8.0 mmol/l) to reduce the risk of maternal hypoglycaemia whilst maintaining safe glycaemia. 
• After delivery, the target value can be relaxed to 108-180 mg/dl (6-10 mmol/l).

 

At the Hospital Diabetes Meeting 2023, Dr. Florence Brown, from the Joslin Diabetes Center, shared the different glycemic targets that are used in her center based on 4 distinct periods during delivery:

• The 1st period is antepartum when women can still eat: target glycemic range 70-140 mg/dl (3.9-6.1 mmol/l), as you generally don't want people dropping below 70 mg/dl (3.9 mmol/l) in the hospital setting.
• The 2nd period is during labor or prior to a scheduled cesarean section when women are not allowed to eat any longer: target glycemic range 80-110 mg/dl (4.4-6.1 mmol/l).
• The 3rd period is postpartum when women are still not allowed to eat: target glycemic range 100-150 mg/dl (5.6-8.3 mmol/l).
• The 4rd and final period is after delivery when women can resume eating: target glycemic range 70-180 mg/dl (3.9-10 mmol/l), which is the standard non-pregnancy target range.

 

 

#2 What do the guidelines say about closed-loop systems in pregnancy?

"At present only one system is licensed (CamAPS FX). It may be appropriate to continue a commercial HCL system that is unlicensed in pregnancy if benefits outweigh risks, especially in situations where underlying glycemic levels on manual pump therapy are suboptimal." - ABCD-DTN Best Practice Guide for Hybrid Closed-Loop Therapy. Diabetic Medicine 2023.

 

CGM in pregnancy

Several studies, including Abbott and Dexcom, have demonstrated that the accuracy of sensors is not impacted by pregnancy physiology.

However, it is noteworthy that the most commonly utilized sensors (like Dexcom G6 and Guardian sensors) only hold a CE-label and lack FDA accreditation fur use in pregnancy.

• CE-label (no exeption for use in pregnancy): FreeStyle Libre2, Libre3, Dexcom ONE, Dexcom G6, Dexcom G7, Guardian 3, Guardian 4
• FDA-label: FreeStyle Libre2, Libre3, Dexcom G7.

 

This may explain why the ADA Standards of Care 2023 only recommends CGM in addition to SMBG (Self-Monitoring of Blood Glucose) or fingerpricks.

 

Utilizing CGM during labor and delivery presents additional concerns regarding accuracy, as these women may receive a significant amount of intravenous fluids and they may have considerable peripheral edema.

It is advisable to avoid positioning the blood pressure cuff above the CGM, as it has been observed that this can lead to a decrease in the accuracy of CGMs, which are generally placed on the upper arms during the end of pregnancy.

 

Closed-loop systems in pregnancy

There have been several larger randomized controlled trials (RCTs) completed recently, such as the AIDAPT study on the CamAPS system and CRISTAL with the 780G Medtronic HCL system.

However, the results of these trials have not yet been published.

Additionally, the ongoing CIRCUIT trial is evaluating Tandem Control IQ in pregnancy, with completion expected in early 2024.

 

Currently, the only closed-loop system with official indication for use in pregnancy is the CamAPS FX, which is not yet available in many countries.

 

While closed-loop systems are being used more frequently in pregnancy, they are not yet officially recommended in most guidelines.

 

The British guidelines on closed-loop systems only make a cautious recommendation, stating that "At present only one system is licensed (CamAPS FX). It may be appropriate to continue a commercial HCL system that is unlicensed in pregnancy if benefits outweigh risks, especially in situations where underlying glycemic levels on manual pump therapy are suboptimal."

 

Closed-loop systems during labor and delivery

"Our patients with type 1 diabetes are all on CGM's and many of them are on insulin pumps. Our standard procedure is to put everybody on an insulin drip once they are NPO. But that has been changing dramatically with our assisted insulin devices and we have been able to allow many of our women to continue their pumps while they are in labour. And then after they deliver continue their insulin pumps. There are many concerns here. Is the patient in excellent control? Can she self manage her diabetes under a variety of circumstances? There are also concerns that there maybe an obstetrical event that needs to be managed quickly. What happens to the management in that situation? Are all pumps able to transition and maintain the targets that we are aiming for in these different phases of labor and delivery?" - Dr Florence Brown (Joslin Diabetes Center) - Hospital Diabetes Meeting 2023

 

If few studies evaluated insulin pumps and closed-loop systems during pregnancy, even fewer studied it during labor and delivery.

 

A "position statement" from the British Diabetes Association (Dashora et al. Diabetic medicine 2021) recommends that you continue to use your CGM, insulin pump and/or closed-loop system during labor and delivery because it gives better glycemic control, provided the following conditions are met (cfr also Avari et al. JDST 2022):

• Glycemia should be checked once an hour via CGM or finger prick
• If an intravenous insulin strip is used, it is best to use a finger prick instead of CGM
• If general anesthesia is used, it is best to check glycemia every half hour until the patient regains consciousness
• The glycemia and the given insulin dose should be well documented
• If the glycemia at 2 consecutive times is >144 mg/dl (8 mmol/l), switch to an intravenous insulin drip
• The infusion set of the pump must be placed at a sufficient distance from the diathermy pads, and for diathermy (used in cesarean sections) only Teflon cannulas should be used
• After delivery, the person with diabetes or her partner should adjust the insulin settings in the pump or closed-loop system to pre-pregnancy values
• The person with diabetes and her partner must have the confidence to operate the insulin pump and/or closed-loop system during labor and delivery
• The obstetrician and anesthesiologist must agree to the continued use of the insulin pump and/or closed-loop system, have a good understanding of its operation, and work closely with the diabetes team

  

Training of the delivery team is a major barrier

It is not easy to keep up with the constantly changing range of insulin pumps and closed-loop systems.

This is true for diabetes educators and endocrinologists, but even more so for those on the delivery team, gynecologists and anesthesiologists.

On top of this, they also have even less opportunity to maintain their knowledge through experience.

This is a major barrier to allowing the use of insulin pumps and closed-loop systems during labor and delivery.

 

If you are a center seeking to provide pregnant women with this option, you can refer the delivery team to Diabetotech's video programs.

These dutch programs cover the complete education of a closed-loop system in just 1 to 2 hours per system (accessible on YouTube or with a certificate).

Please note that an English-language version will be available after the summer of 2023.

 

 

#3 General tips for closed-loop systems in pregnancy

"It's important to manage expectations. Pregnancy is still twice as much work as not being pregnant with type 1 diabetes, even with a closed-loop system."

 

Expect fluctuations in insulin requirement

Be prepared for the following fluctuations in insulin levels during pregnancy (see figure from dr. Sarit Polsky, presented at CEU 2022):

• In the first trimester, the insulin requirement can drop.
• From 16-20 weeks, the insulin requirement begins to increase, with slightly more increase in bolus insulin than basal insulin (O'Malley et al. DTT 2021). Over the course of pregnancy, insulin requirements may double from the preconception doses.
• After childbirth, the insulin requirement drops very sharply. Usually it is recommended to return to the preconception insulin dose, although insulin requirements can drop to 50-60% of this preconception dose. That's why sometimes it is recommended to use even lower insulin doses then the ones before pregnancy (eg around 20% less).

• When breastfeeding, insulin requirements are often 10-20% lower compared to pre-pregnancy insulin requirements.

 

If you experience a sudden drop in insulin requirement during the final weeks of pregnancy, it could be an indicator of a potential issue with the baby. It is important to notify your gynecologist in this situation.

 

Adjust the target pregnancy rate in the reports

To properly assess TIR in pregnancy, the limits should be adjusted to 63-140 mg/dl (3.5-7.8 mmol/).

 

Here's how to do this depending on the platform:

• In LibreView, in the person's report with diabetes, go to report settings (blue button at the bottom). (see figure)
• In Dexcom Clarity, in the patient interactive report, go to glucose ranges for patients (left sidebar). (see figure)
• In CareLink, you can only change the target value in your personal profile as a healthcare provider (upper right corner). This then applies to all your patients until you change it again. (see figure)
• In Glooko, you can adjust data settings in the patient profile (press profile next to the patient's name). (see figure)
• In Nightscout, when you pull reports, you can set the desired target value at the top. (see figure)

 

After delivery, remember to adjust the target value back in the reports.

 

Use the lowest target value available for the system

See below for details per system

 

Correct for hyperglycemia carefully and often

Aggressive management of hyperglycemia is crucial during pregnancy:

• Set a high alert to notice you when to act, such as 140-160 mg/dl (8-9 mmol/l).
• Use a manual bolus, "false carbs" or Boost-function to correct hyperglycemia, depending on the system you use.
• Use the bolus calculator, if available.
• Do this no more then once every 2 hours to avoid insulin stacking.

 

Get the diet right

"Diabetes in pregnancy is 90% diet, 10% insulin."

• Choose foods with a low glycemic index (high in fibre, avoid processed food)
• Be sure to be accurate in carb counting and consider keeping a food diary
• Avoid high carb diets. It might be necessary to reduce carbs to avoid postprandial hyperglycemia, especially in the 3rd trimester of pregnancy.

 

In this video from the ABDC-DTNUK it is suggested to take a diet of no more then 150-200 grams of carbs per day:

• Breakfast 20 gram
• Lunch & dinner 40-60 gram
• Mid-meal 10-20 gram

 

Get the insulin in ahead of meals

It's important to bolus before meals (especially important with breakfast):

• 10-15 minutes before in 1st trimester
• 20-30 minutes before in 2nd trimester
• 30-45 minutes before in 3rd trimester

 

Avoid overcorrection of hypoglycemia

• Check hypoglycemia with a finger prick test before correcting and before re-treating for persistent hypoglycemia.
• Caution: hypoglycemia in pregnancy is a glucose < 63 mg/dl (3.5 mmol/l), not < 70 mg/dl (3.9 mmol/l).
• When experiencing hypoglycemia, take fewer carbs if you use a closed-loop system (eg 7 grams instead of 10 grams), especially if you see that you didn't receive much insulin lately.

 

Think of ketoacidosis

Pregnant women with type 1 diabetes have an increased risk of ketoacidosis.

• This is concerning because ketoacidosis is toxic to the baby and increases the risk of miscarriage (16% in this 2017 US study).
• Pregnant women who are not feeling well with vomiting, abdominal pain or ketones should be examined for ketoacidosis, even with normal glycemia.

 

Note the following education points to prevent ketoacidosis: (DTNUK Guidelines Diabetes technology in Pregnancy 2020)

• Always carry an insulin pen with short-acting insulin.
• Have a ketone meter available and test for ketones from a glycemia of >180 mg/dl or 10 mmol/l (i.e. faster than outside pregnancy).
• React if ketones are >1 mmol/l (i.e. faster than outside pregnancy): give an insulin bolus with an insulin pen and change the infusion set and reservoir.

  

Prevent hypoglycemia

The risk of hypoglycemia is especially high in the first trimester and early 2nd trimester (up to 20 weeks) and just after birth.

 

Therefore, emphasize the following education points:

• Always have glucagon with you and know how to use it.
• Inform family and work colleagues about the high risk of severe hypoglycemia especially in the 1st and 2nd trimester, and what to do then.
• Take an extra snack of, say, 10 to 15 grams of carbohydrates after each breastfeeding session.

 

Infusion Set

• Change the infusion set every 2-3 days and set an alarm for this task.
• Check glycemia 2 hours after each infusion set change to ensure that it is working correctly.
• Change the infusion set preferably in the morning to be able to check its correctness.
• To avoid interfering with a possible cesarean section, it is recommended to place the infusion set on the flanks, buttocks, and thighs, particularly after week 30.
• If you experience issues with the kinking of the Teflon cannula, use a steel cannula instead. Note that the steel cannula should not be used with diathermy.

 

Follow pregnant women with type 1 diabetes every 1-2 weeks

Pregnant women with type 1 diabetes typically have appointments with their healthcare providers every 1-2 weeks to receive customized education and adjust the settings of their closed-loop system.

Since closed-loop systems may revert back to manual mode, it is crucial to adjust the pre-programmed basal insulin every 2 weeks to accommodate changing insulin requirements.

 

During and after delivery

Women with type 1 diabetes typically undergo induced delivery between 36-38 weeks of pregnancy to prevent complications.

Depending on the country, there is a higher likelihood of cesarean section over natural delivery.

 

For those who opt for natural delivery, it can be considered as a form of exercise, and insulin requirements may decrease.

However, general recommendations for adjustments to closed-loop settings are difficult to provide, as adjustments should be made according to glucose levels during labor or delivery.

 

After delivery, it is generally recommended to return to pre-pregnancy insulin settings.

However, some colleagues suggest lowering insulin settings further, as postpartum insulin requirements can decrease to 50-60% of pre-pregnancy insulin need.

It is best to prepare postpartum settings and program them in the closed-loop system ahead of time, if possible.

 

Additionally, insulin requirements during breastfeeding are typically 10-20% lower than pre-pregnancy insulin needs.

 

Sources

• Szmuilowicz et al. DTT 2023
• Top tips during pregnancy. DTN-UK
• DTN-UK Best Practice Guide for Diabetes Technology in Pregnancy 2020

 

 

CAUTION: Only CamAPS has been approved for use in pregnancy, while all other closed-loop systems are used off-label during pregnancy.

It is important to note that these recommendations are based on current knowledge and may evolve in the future.

This is not medical advice, and it is recommended that you discuss the use of closed-loop systems during pregnancy with your healthcare provider.

It should also be emphasized that recommendations regarding HCL systems during pregnancy may vary on an individual basis,

and larger studies are needed to formulate better guidelines.

  

 

#4 Mylife Loop

 

CamAPS FX is the only algorithm that has a CE label for use in pregnant women with type 1 diabetes.

The advantage is that there is already a lot of experience, as you can see in this YouTube video.

 

Adjustable parameters

In Mylife Loop, you can customize the following:

• The target value (80-200 mg/dl or 4.4-11.1 mmol/l) and the carb ratio.
• There is also an optional Ease-Off function that you can use to temporarily receive less insulin, and an optional Boost function to temporarily get more insulin
• When starting the mylife CamAPS app, you can set the weight and total daily dose of insulin. The weight can be adjusted afterwards.

 

You can NOT adjust the basal insulin rate, the insulin sensitivity, and the duration of insulin action. Those are calculated by the algorithm.

 

During pregnancy

During pregnancy, it is recommended to lower the target value:

• In 1st trimester lower the target value to 100 mg/dl (5.5 mmol/l).
• In 2nd and 3nd trimester the target value can be lowered to 90 mg/dl (5.0 mmol/l) during the day and 80 mg/dl (4.5 mmol/l) from bedtime to waking
• Lowering the target is best feasible if the glycemic variability is low (standard deviation <2% or coefficient of variation <33%).
• If someone has a lot of hypoglycemia, you can temporarily increase the target value to for example 104 mg/dl (5.8 mmol/l). Remember to try to lower the target value again after a few days.

 

Other recommendations for the use of the CamAPS algorithm in pregnancy are:

• Correct (postprandial) hyperglycemia with the Boost function.
• If you experience postprandial hyperglycemia after breakfast, you can consider using the lowest target value during breakfast (80 mg/dl or 4.5 mmol/l). You can also also consider to program the Boost function the night before: to start from 1 hour before breakfast.
• Adjust the weight regularly. The weight helps the algorithm in the post-meal period so it is very important in pregnancy (less so outside pregnancy when you are not aiming for these very tight post-meal targets).
• Do not use ‘algorithm driven insulin’ or ‘basal’ as reported by stats - to calculate basal daily dose for the adjustment of pre-programmed basal. The algorithm has significant post-prandial function so algorithm insulin-delivery is higher than pump basal. It is recommended to use a standard basal % (for example 30-40%) from the average total daily insulin dose to estimate daily basal requirements.
• Increase the maximum bolus of the Ypsopump if necessary. 

 

These practical tips can also be found in this leaflet.

 

During and after delivery

During and after delivery, it is best to set the parameters as follows:

• Raise the target value to for example 104-108 mg/dl or 5.8-6.0 mmol/l - if a ceasarian is planned, you can raise the target from the time the woman is sober (the night before)
• When trending to hypoglycemia use Ease-off and/or set a (temporary) higher target value (for example 140-160 mg/dl or 8-9 mmol/l) - this approach can also be used during breastfeeding
• When experiencing hyperglycemia during delivery, Boost can be used.
• After delivery: increase carbohydrate ratio to prepartum level (write this down somewhere so you have it by hand when you need it)

 

More validated guidelines on how to use CamAPS during pregnancy and delivery will be shared at ADA2023.

 

Studies

• Murphy et al. Diabetes Care 2-2011 and Murphy et al. Diabetes Care 12-2011: n=10 and n=12 pregnant women with type 1 diabetes on CamAPS for 24 hours
• Stewart et al. NEJM 2016: n=16 pregnant women with type 1 diabetes on CamAPS for 28 days (overnight only)
• Steward et al. Diabetes Care 2018: n=16 pregnant women with type 1 diabetes on CamAPS for 28 days (all day), with possibility of continued use
• Steward et al. DTT 2018: n=27 pregnant women with type 1 diabetes used CamAPS during delivery
• According to Rankin et al. DTT 2023: evaluation of caregiver experiences during the AiDAPT study
• AiDAPT study: randomized trial in n=124 pregnant women with type 1 diabetes (results expected in late 2023 or ATTD2024)

 

 

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#5 MiniMed 780G

  

Adjustable parameters

In the MiniMed 780G, you can customize the following items:

• the target value (100-120 mg/dl or 5.6-6.7 mmol/l),
• the active insulin time (2-6 hours),
• and the carb ratio.
• There is also an optional temporary target (150 mg/dl or 8.3 mmol/l) that you can use for exercise.

 

You can NOT adjust the basal insulin rate and the insulin sensitivity. Those are calculated by the algorithm. The target value for the autocorrection boluses is fixed at 120 mg/dl or 6.7 mmol/l.

 

During pregnancy

During pregnancy, it is recommended to

• use the lowest target value of 100 mg/dl or 5.6 mmol/l,
• and the lowest active insulin time of 2 hours.

 

To avoid postprandial hyperglycemia, the following steps are recommended:

• Reduce the carb ratio as much as possible.
• If further lowering of the carb ratio is not possible because the system will apply more Safe Meal Bolus, you can try to take fewer carbs with the meal.
• If Safe Meal Bolus is still occurring, increase the carb ratio.
• If necessary, add false carbohydrates with the meal (20 to 100% of the carbohydrates you will eat) or between meals.

 

During and after delivery

During and after delivery, it is best to set the parameters as follows:

• Set the target value at 110 or 120 mg/dl (6.1 or 6.7 mmol/l), although you can also try leaving it at 100 mg/dl (5.6 mmol/l).
• The active insulin time can remain unchanged.
• If trending to hypoglycemia, you can use the temporary target - also applicable when breastfeeding
• After delivery: increase the carbohydrate ratio by at least 50% (up to 200% if necessary in case of breastfeeding)

 

Studies

• Dodesini et al. DTT 2023: retrospective study in 8 women with type 1 diabetes
• CRISTAL study: randomized trial in n=92 pregnant women with type 1 diabetes (n=46 MiniMed 780G and n=46 standard of care) - Results expected by the end of 2023/2024

 

 

#6 Tandem Control IQ

 

 

 

Adjustable parameters

In Tandem Control IQ, you can customize the following items:

• the basal insulin rate (different profiles possible),
• the correction factor,
• and the carb ratio.
• There is also a Sleep Activity with a lower target range of 112.5-120 mg/dl (6.25-6.7 mmol/l) and a Exercise Activity with a higher target value of 140-160 mg/dl (7.8-8.9 mmol/l).
• When starting Control IQ, you can enter the total daily insulin dose and weight. Both can be adjusted afterwards.

 

You can NOT adjust the target value (fixed at 112.5-160 mg/dl or 6.25-8.9 mmol/l), the duration of insulin action (fixed at 5 hours), and the target value for correction boluses (fixed at 110 mg/dl or 6.1 mmol/l).

 

During pregnancy

During pregnancy, it is recommended to use the Sleep Activity 24 hours a day:

• You can set a sleep schedule each day from 0h to 23h95.
• You can check if sleep mode is on by checking if a ZZZ is visible in the pump screen in the upper left corner.
• In Sleep Activity, the algorithm does not give automatic correction boluses! It is recommended to give a manual correction bolus before bedtime if the glycemia is elevated, and also when the pump suggests it.

 

The basal insulin rate, carb ratio and correction factor must be adjusted to the changing insulin requirement of the pregnant woman. Additional recommendations are:

• Make aggressive insulin adjustments in comparison to standard pump at ~20 weeks gestation (program basal rates much higher than delivered basal insulin i.e. 25% higher total daily basal)
• Use a correction factor that is at least as strong as 90 ÷ total daily insulin mmol/l (1620 ÷ TDI in mg/dl)
• Individualize but consider carb ratios that are at least as strong as 400 ÷ total daily insulin dose (units/g)

 

Other recommendations for the use of Tandem Control IQ in pregnancy are:

• Do not accept reduction of meal boluses: The Tandem Control IQ bolus calculator offers the option of reducing the meal bolus if the glycemia is <110 mg/dl (6.1 mmol/l) (see figure). Since such strict glycemia is just desirable in pregnancy, it is recommended not to accept this optional meal bolus suggestion should the pump suggest it.
• Ensure maximum bolus limits are set slightly above expected bolus dosages. You can set this between 10 and 25 E. If you need more than 25 E for the meal, you will get 2 alarms. At the first alarm, confirm that you want to get the maximum bolus set. At the second alarm, you have to confirm that you also want to get the rest of the bolus. The 2nd alarm is only available in one of the updates of Control IQ, so be sure to work with the latest update of the pump software.
• If you use the Exercise Activity, don't forget to manually stop this at the end of the exercise. Also check if the Sleep Activity turns back on when you stop the Exercise Activity. If you are working with the latest software update, this happens automatically.
• Adjust total insulin dose and weight regularly in the Control IQ settings.

 

During and after delivery

During and after delivery, it is best to set the parameters as follows:

• Start the "postpartum profile" when starting labor or 1 hour before a planned cesarean section. This postpartum profile can easily be preset in the Tandem pump a few weeks before delivery.
• The Sleep Activity can stay on during labor and delivery, in case of a trend towards hypoglycemia it is best to turn it off. After delivery you can stop the Sleep Activity.
• The Exercise Activity can be used in case of trend towards hypoglycemia, and also during breastfeeding.

 

Studies

• Wang et al. Diabetic Medicine 2023: retrospective study in n=8 pregnant women with type 1 diabetes
• CIRCUIT trial: randomized study in n=66 women with type 1 diabetes (Tandem Control IQ or standard treatment) - Results expected in 2026

 

 

#7 Omnipod 5 

 

Adjustable parameters

In Omnipod 5, you can adjust the following items:

• the target value (110-150 mg/dl or 6.1-8.3 mmol/l) and the carb ratio.
• You can also adjust the correction factor, the duration of insulin action and the "Correct Above" value, although these parameters are only used when you use the bolus calculator.
• There is also an "Activity Feature" with a higher target value (150 mg/dl or 8.3 mmol/l) to be used when exercising.
• When starting Omnipod 5, you must enter your total daily insulin dose. Afterwards, it is copied from the previous pod, so you cannot adjust it yourself.

 

You can NOT adjust the basal insulin rate and the insulin sensitivity and the duration of insulin action for calculating the automated basal insulin. Those are calculated by the algorithm.

 

During and after pregnancy

We did not find any case reports or tips online about using Omnipod 5 in pregnancy, other than that it is best to opt for the lowest target value of 110 mg/dl (6.1 mmol/l).

 

Caution: Omnipod pods can only hold 200 E of insulin, but in the course of pregnancy the insulin requirement can increase to 60-80 E per day As a result, you may have to replace the Omnipod every 2 days instead of every 3 days, which might increase the cost.

 

 

#8 Diabeloop

  

Adjustable parameters

At Diabeloop, you can adjust the following:

• the target value 100-130 mg/dl (5.6-7.2 mmol/l),
• the aggressiveness at meals, at normoglycemia and at hyperglycemia,
• and the hypoglycemia threshold.
• There is also a "Sports Activity" you can use when exercising, and a Zen Mode that you can use if you don't want to be disturbed.
• When starting Diabeloop, you must enter your total daily insulin dose and your weight, as well as the average number of grams of carbs you eat at breakfast, lunch and dinner. These are all adjustable afterwards.

 

You can NOT adjust the basal insulin rate, the carb ratio, the insulin sensitivity, and the duration of insulin action. Those are calculated by the algorithm. The hyperglycemia threshold is fixed at 180 mg/dl (10 mmol/l).  !Addendum: although carb ratio are not modified as such, you can modulate the meal reactivity (from 50 to 200 %). And regarding insulin sensitivity, you can change the Total Daily Dose, which is a surrogate for insulin sensitivity.

 

Pregnancy and childbirth

It is recommended to use the lowest target value of 100 mg/dl (5.6 mmol/l).

Recommendations for the use of DBLG1 in pregnancy are:

• Use the lowest target value of 100 mg/dl (5.6 mmol/l).
• Increase total daily insulin dose on a regularly basis after week 12 (probably every 2 weeks), and increase agressiveness at meals as well.

 

Study

• Pemfronis et al. NCT05661149: retrospective study of n=14 pregnant women with type 1 diabetes on MiniMed 780G, Tandem Control IQ and DBLG1

 

 

#9 AndroidAPS

 

Adjustable parameters

In AndroidAPS, you can customize the following:

• the target value (80-200 mg/dl or 4.4-11.1 mmol/l),
• the basal insulin rate (different profiles possible),
• the carb ratio,
• the insulin sensitivity,
• and duration of insulin action (5-8 hours).
• You can set any temporary target and/or % of insulin delivery. Typically you also set a premeal range to use before meals (instead of prebolusing).
• You can use the Autosens function to adjust the basal insulin rate, the insulin sensitivity and the target value, according to the insulin sensitivity of the last 8 to 24 hours.
• You can use the UAM (unannounced meal) function so the algorithm can automatically detect meals (in combination with OpenAPS SMB).
• At the startup of AndroidAPS you can set different parameters which are all modifiable: the type of algorithm (OpenAPS AMA or OpenAPS SMB), the maximum insulin on board, the maximum daily safety multiplier and the current basal rate multiplier, the min_5min_carb impact, the bolus snooze slide divider, the maximum meal absorption, and the maximum and minimum autosens ratio.

 

It is characteristic of AndroidAPS that all parameters are adjustable.

 

During and after pregnancy

We did not find much guidance on how to use AndroidAPS in pregnancy. It would be logical to

• Adjust the target value, basal insulin rate, carb ratio and insulin sensitivity based on individual need.
• Use OpenAPS SMB (instead of OpenAPS AMA) and use Autosens.
• Change your patient type to "pregnant", because this will allow the algorithm to be more agressive in insulin delivery. Here you can see the changes the algorithm makes to the hardcore limits if you change your patient type.
• Preset a postpartum profile in your AndroidAPS app to use during/after delivery.
• (Join the DIY Looping and Pregnancy Facebook group)

 

Studies

• Schütz-Fuhrmann et al. JDST 2020: case report n=1 pregnant woman with type 1 diabetes on AndroidAPS
• Waikar et al. Clinical Diabetes 2021: case report n=1 pregnant woman with type 1 diabetes on AndroidAPS
• Szmuilowicz et al. DTT 2023: expert guidance on off-label use of hybrid closed-loop therapy in pregnancies complicated by diabetes

 

 

#10 DIY Loop

 

Adjustable parameters

In DIY Loop 3.0, you can customize the following things:

• the target value range (87-180 mg/dl or 4.8-10 mmol/l),
• the basal insulin rate,
• the carb ratio,
• the insulin sensitivity,
• and the Glucose Safety Limit (67-110 mg/dl or 3.7-6.0 mmol/l).
• You can set a Premeal Range to be used before meals (instead of prebolsing) adjustable between the Glucose Safety Limit and 130 mg/dl (7.2 mmol/l).
• You can set any "Override" with an adjustment of your target value and/or % of your insulin need.
• You can choose between 2 insulin dosing strategies: Temp Basal Only or Automatic Bolus.
• When starting DIY Loop, you must also set the maximum basal and maximum bolus, and the insulin model (children or adults: peak insulin action 60 min and 75 min, respectively). These can all be changed afterwards.

 

You can NOT modify the duration of insulin action (fixed at 6 hours).

 

During and after pregnancy

Here are some recommendations we found for using DIY Loop during pregnancy:

• Adjust the target value, basal insulin rate, carb ratio and insulin sensitivity based on individual need.
• Target value can be set at 100-110 mg/dl (5.6-6.1 mmol/l).
• Premeal Range can be at 85-90 mg/dl (4.7-5.0 mmol/l), although the premeal feature available in DIY looping systems is not typically as helpful in reducing postprandial glucose elevations.
• Use the lowest Glucose Safety Limit (67 mg/dl or 3.7 mmol/l).
• Adjust meal bolus types to accommodate delayed gastric emptying as pregnancy progresses: Except for breakfast where Lollipop (2 h) bolus is often used, Taco (3 h) or Pizza (4 h) are most commonly needed for meals that have even modest amounts of fat by mid-second/third trimester
• You cannot preset a postpartum profile, so you have to keep this ready to enter in your Loop app after delivery.
• (Join the DIY Looping and Pregnancy Facebook group)

 

Studies

• Schütz et al. Poster at ATTD2021: case report n=3 pregnant women with type 1 diabetes on DIY Loop and n=1 on AAPS
• Bukhari et al. BMJ 2021: case report n=1 pregnant woman with type 1 diabetes on DIY Loop
• Szmuilowicz et al. DTT 2023: expert guidance on off-label use of hybrid closed-loop therapy in pregnancies complicated by diabetes
• Halperin et al: an evaluation of open-source automated insulin dosing (AID) systems in n=100 pregnant patients with type 1 diabetes => results in june 2023

 

 

 

#11 Pregnancy-specific closed-loop system

 

 

At ATTD2023, the LOIS-P consortium (Longitudinal Observation of Insulin Requirements and Sensor Use in Pregnancy) showed the first results of a closed-loop system developed specifically for pregnancy.

 

It consists of

• a Dexcom G6 sensor,
• a Tandem t:AP insulin pump (similar to the t:slim X2),
• and the iAPS algorithm from Harvard adapted to pregnancy.

 

In this study, 10 pregnant women with type 1 diabetes on a (manual) insulin pump were included during their 2nd trimester of pregnancy.

 

The results were very positive:

• The TIR (63-140 mg/dl or 3.5-7.8 mmol/l) increased from 65% (during 7-day run-in period) to 79%,
• the TBR (<63 mg/dl - 3.5 mmol/l) decreased from 3.7% to 1.6%
• and time in auto-mode was >90%.

 

Although the results have not yet been published, these initial findings are very promising.

 

Studies

• Dassau et al. NCT04492566: prospective study in n=21 pregnant women with type 1 diabetes on Zone-MPC in an iAPS platform

 

 

All in all, the use of closed-loop systems in pregnant women with type 1 diabetes is slowly beginning to increase, and initial results show that it is safe and effective (although for now the data is very limited).

 

We are optimistic that this will soon be included in guidelines and that expected studies will help us to guide pregnant women appropriately.

 

The benefits of such systems could be enormous, since they could help drastically reduce the number of complications, miscarriages and babies that are "large-for-gestational-age".

 

To make choosing a closed-loop system easier for people with type 1 diabetes, we have developed a 10 best closed-loop systems cheat sheet.

Get the cheat sheet here,

so you can select the closed-loop system that would be a good fit for you or your patient!

 

Let's spread the word and keep up our efforts towards improving treatment options for moms with type 1 diabetes!

 

Kind regards,

Inge 

 

 

 

PS: As icing on the cake, read below the promising experiences of 4 early adopters who used the Tandem Control IQ in their pregnancies.

 

Theme 1: Satisfaction from improved glycaemic control

‘Everything was better with this pregnancy. There was a huge difference compared to injections and a glucometer. [Control-IQ] encourages you to make corrections more easily'. Case #1

‘I felt more control over my blood sugars. My first A1c was 6.9% which was a lot lower compared to this point in my previous pregnancy on my previous insulin pump, and I had only been on [Control-IQ] for 2–3 months then’. Case #2

'With Tandem your blood sugars and control are so much better. My A1c by the end of pregnancy was 2 points lower than at the same point in my first pregnancy. My baby was 1 pound lighter than my first baby even though I was further into term. I didn't know that my A1c could be at 5.8% and I didn't think I was doing anything major to make it that way'. Case #2

‘There was more freedom with Control-IQ. Day to day activities were more restrictive without it’. Case #4

‘[Control-IQ] decreased the severity and frequency of lows. I corrected with less carbohydrates than my previous pump. If I was on my previous pump, I would correct with 15 g, but I only needed 8 g with Tandem’. Case #2

Theme 2: Improvement in sleep

‘Sleep was the biggest difference compared to multiple daily injections and a glucometer in my first pregnancy. The pump can fix nighttime lows for you, I didn't need to wake up and wasn't aware that it had even happened’. Case #1

‘[Control-IQ] keeps you even and steady overnight’. Case #2

‘Nights were better. Overall sleep was better. The biggest advantage to the system was that I could go to bed with higher or lower blood sugars and know the system could make adjustments for me. Sleep is very valuable, so it was nice that my diabetes was not waking me up’. Case #3

‘Tandem has been good at dealing with lows which provides more security overnight when I have no hypoglycemia awareness’. Case #4

Theme 3: Trust in the algorithm and stress relief

‘Control-IQ takes away the stress and anxiety from chasing blood sugars overnight. I was also able to make small titrations due to the ease of calculations. I could even be able to correct an 8.0 mmol/L without dropping low’. Case #1

‘[Control-IQ] takes the guess work out, it helps after immediately having a baby because you are not thinking of yourself. [ControlIQ] keeps you level’. Case #2

‘[Control-IQ] provided more freedom than being constantly tied to your diabetes devices. In my first pregnancy I was testing my blood sugar 12 to 14 times a day because of anxiety, but I can rely on [Control-IQ] to keep me in target range. I spent less time during the day thinking about diabetes’. Case #2

‘There were fewer variable [glucose records] because I could trust the [Control-IQ] system. I did not have to focus on my diabetes as much and could just focus on my pregnancy. My experience with [Control-IQ] was fantastic. It reduced the overall burden of diabetes’. Case #3

Theme 4: Lack of familiarity with T1D self-management, technology and specifically the Control-IQ™ algorithm was a cause of anxiety for staff on the postpartum ward while participants were admitted to hospital

‘Most of the labour and delivery team was okay with [Control-IQ] and preferred it. In postpartum however, the nurses had their own charting and made you check your blood sugar anyways even though I had a CGM. They wanted me to have their carbs and their insulin, and everyone had a different approach. It was confusing for both me and the nurses. They weren't managing my diabetes, but they believed they needed to chart my information to properly meet their job requirements. Most people didn't know anything about Tandem. I think it would be helpful if there was more clarity on how to work with someone with diabetes who is self-managing’. Case #1

‘There was a lot of ignorance from the postpartum staff, comments made from staff such as “wow, that's not good” when I told them I had a blood sugar of 11.8 mmol/L. Another nurse said, "that's high, hey?" to a blood sugar of 8.8 mmol/L. And one of the nurses changed my diet order to a "diabetic diet" but I should have been on a ‘regular postpartum diet’ order which was made clear by my physician in the orders'. Case #3