- Guest: Professor Eleanor Scott (Leeds Teaching Hospitals NHS Trust)
- Host: John Pemberton
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Why this episode exists
Pregnancy with type 1 diabetes requires navigating intense physiological changes, shifting insulin needs, tight glucose targets, and an overwhelming amount of clinical information, often delivered at the worst possible time. Professor Eleanor Scott, one of the UK’s leading experts in pregnancy and diabetes, breaks down what actually matters: the glucose targets that protect both mother and baby, which technologies have robust evidence, how to handle the dramatic insulin swings across trimesters, and why planning (when possible) makes such a difference. This is the evidence-based roadmap that cuts through the noise.
The pregnancy roadmap
- Pre-pregnancy: Optimize glucose control (HbA1c <48 mmol/mol / 6.5%), start 5mg folic acid, check vitamin D, aim for 70% time in pregnancy range (3.5-7.8 mmol/L or 63-140 mg/dL) ideally for at least one month before conception.
- First trimester (weeks 1–12): Increased insulin sensitivity, frequent hypos, nausea complicates bolusing — this is survival mode with high variability.
- Second and third trimesters (weeks 13–40): Insulin resistance climbs dramatically — insulin-to-carb ratios can increase 3–5× baseline, requiring aggressive weekly adjustments.
- Delivery and postpartum: Insulin needs drop instantly back to pre-pregnancy levels once the placenta is delivered; breastfeeding may require further reductions.
- Technology first-line: Pregnancy-specific hybrid closed-loop systems (CamAPS FX) and CGM are now standard care — they reduce burden, improve outcomes, and save the NHS money.
Key takeaways
1) Glucose targets are tight for a reason
The pregnancy glucose target range is 3.5–7.8 mmol/L (63–140 mg/dL), with a goal of 70% time in range. This is tighter than the standard type 1 diabetes range (3.9–10.0 mmol/L) because babies are extremely sensitive to raised glucose — high levels increase risk of miscarriage, congenital malformations, preterm delivery, large babies, and neonatal intensive care admissions. The tighter target reproduces near-normal physiology as closely as possible, protecting both mother and baby.
2) Planning pregnancy matters — but unplanned is not catastrophic
Ideally, glucose control should be optimized before conception (HbA1c <48 mmol/mol, 70% time in pregnancy range for at least one cycle). High HbA1c at conception (>80s mmol/mol) increases risks, but absolute risk of complications is still around 10% — not inevitable. If pregnancy is unplanned, contact your diabetes team immediately. Every improvement in glucose control from that point forward reduces risk. The first 12 weeks are critical for baby development, but early intervention still makes a substantial difference.
3) First trimester: insulin sensitivity and chaos
The first 12 weeks bring increased insulin sensitivity, frequent hypos, nausea, vomiting, and highly variable glucose levels. Many women struggle despite doing “everything right” — this is normal physiology, not failure. Practical strategies include reducing basal insulin as needed, bolusing after meals if nausea makes pre-bolusing risky, eating smaller frequent meals, and accepting that glucose control will be imperfect during this phase. Pregnancy-specific hybrid closed-loop systems handle this variability far better than manual adjustments.
4) Second & third trimesters: massive insulin resistance
Insulin needs climb dramatically — insulin-to-carb ratios can increase from 1:10 to 1:3 or even 1:2. This is not a sign of poor control; it is expected physiology driven by placental hormones. Basal rates and bolus doses need aggressive weekly adjustments to keep up. Pre-bolusing becomes critical (15–20 minutes with hybrid closed-loop, previously 30–45 minutes on injections). High glucose during this phase drives excessive fetal growth (macrosomia), increasing risk of delivery complications and neonatal hypoglycemia.
5) CGM is non-negotiable
The CONCEPTT trial showed that CGM in pregnancy improves time in range, reduces large-for-gestational-age babies, lowers preterm delivery rates, and cuts neonatal intensive care admissions. Real-world NHS data confirms these benefits — and CGM saves the NHS £9.5 million per year across England. Fingerprick testing is inadequate for the tight control pregnancy demands. CGM is now standard care for pregnancy with type 1 diabetes in the UK.
6) Hybrid closed-loop: pregnancy-specific systems win
Not all hybrid closed-loop systems are equal in pregnancy. The CamAPS FX system is the only one with robust randomized controlled trial evidence (AiDAPT) showing improved time in range, reduced gestational weight gain (3.7 kg less), lower rates of large-for-gestational-age babies, reduced neonatal hypoglycemia, and less maternal burden. It was developed specifically for pregnancy with a personal glucose target as low as 4.4 mmol/L (80 mg/dL) and an adaptive algorithm (exponential forgetting) that prioritizes recent glucose data over historical patterns — essential in pregnancy’s rapidly changing physiology.
The Medtronic 780G has a CE mark for pregnancy but did not show significant improvement in time in range in the CRISTAL trial. Real-world data shows higher gestational weight gain and larger babies compared to CamAPS. Other systems (Omnipod 5, Tandem t:slim Control-IQ) are not CE-marked for pregnancy.
NHS England has created a switching fund allowing women to temporarily switch to CamAPS FX for pregnancy, even if they use a different system outside pregnancy. From an evidence perspective, CamAPS FX is first-line for pregnancy unless unavailable.
7) MDI may outperform standard pumps in pregnancy
Audit data suggests that multiple daily injections (MDI) may achieve better outcomes than standard pump therapy (non-hybrid closed-loop) in pregnancy. This likely reflects the complexity of adjusting basal rates, correction factors, and insulin-to-carb ratios simultaneously on pumps — plus the risk of kinked cannulas causing dangerous highs and ketones. MDI simplifies decision-making: adjust long-acting insulin and carb ratios as needed. However, pregnancy-specific hybrid closed-loop systems vastly outperform both MDI and standard pumps.
8) Delivery: insulin needs drop instantly
Once the baby and placenta are delivered, insulin needs return immediately to pre-pregnancy levels. For planned cesarean sections, pumps can be switched to postpartum settings beforehand. A safe starting point is reducing basal insulin by 50% and returning carb ratios to pre-pregnancy levels (or slightly lower if breastfeeding). Hypos are common postpartum if insulin is not reduced quickly enough — this requires proactive planning, not reactive adjustment.
9) Breastfeeding lowers insulin needs further
Breastfeeding uses significant energy, further reducing insulin requirements. Carb ratios may need adjustment (e.g., from 1:10 to 1:12 or 1:15), and having snacks readily available during feeds helps prevent hypos. Milk supply can take a few days to establish, so insulin needs may shift again once breastfeeding is fully established.
10) Lifestyle tactics that help
- Pre-bolus: 15–20 minutes before meals (even on hybrid closed-loop) — this matters more than almost anything else for post-meal glucose.
- Mixed meals: Combine protein, fat, and vegetables with carbohydrate to slow absorption and match insulin action (which peaks ~2 hours).
- Moderate carbohydrate intake: Aim for 30–40% of total intake — large carb loads are harder to match with insulin in pregnancy.
- Walking after meals: 10–15 minutes of light movement post-meal amplifies insulin action and smooths glucose peaks.
- Routine and predictability: Eating similar amounts at similar times helps both hybrid closed-loop algorithms and manual management adapt to changing insulin needs.
- Avoid high-GI snacks: Even snacks matter — high-glycemic snacks spike glucose and contribute to excessive fetal growth.
11) Ketone awareness: act earlier in pregnancy
Diabetic ketoacidosis (DKA) can develop faster in pregnancy and is dangerous for both mother and baby. If glucose is persistently high (>14 mmol/L for 90 minutes) despite insulin corrections, check for pump/cannula issues immediately and check ketones. Seek medical advice if ketones are ≥1.5 mmol/L (much lower threshold than the usual 3.0 mmol/L outside pregnancy). Most maternity assessment units have protocols for managing this, but early action is critical.
12) One high glucose is not catastrophic
Women with type 1 diabetes in pregnancy are understandably anxious about every glucose spike. A single post-meal high (8 or 9 mmol/L) is not going to harm the baby — what matters is sustained high glucose over time. The goal is 70% time in pregnancy range on average over days and weeks, not perfection every hour. Reframe CGM as information, not judgment: “What happened? What’s the likely driver? What’s one tweak for next time?” This reduces anxiety and avoids the paralysis that comes from fear of imperfection.
Practical checklist: planning pregnancy with T1D
3 months before (or as soon as possible):
- Contact your diabetes team to discuss pregnancy planning
- Start 5mg folic acid daily (requires prescription)
- Check vitamin D levels and supplement if needed
- Optimize glucose control: aim for HbA1c <48 mmol/mol (6.5%) and 70% time in pregnancy range (3.5–7.8 mmol/L)
- If not already using CGM, get set up with continuous glucose monitoring
- Discuss switching to a pregnancy-specific hybrid closed-loop system (CamAPS FX is first-line in the UK)
First trimester (weeks 1–12):
- Contact diabetes team as soon as you know you’re pregnant
- Expect increased insulin sensitivity and hypos — reduce basal insulin as needed
- If nauseous, bolus after meals rather than before to avoid hypos from vomiting
- Eat small, frequent mixed meals
- Attend weekly or bi-weekly diabetes clinic appointments for insulin adjustments
- Accept that glucose will be variable — this is normal, not failure
Second and third trimesters (weeks 13–40):
- Expect insulin needs to climb dramatically (3–5× baseline)
- Strengthen insulin-to-carb ratios progressively (don’t wait until glucose is high)
- Pre-bolus 15–20 minutes before meals (with hybrid closed-loop)
- Walk for 10–15 minutes after eating if possible
- Keep carbohydrate intake moderate (30–40% of total intake)
- Choose mixed meals (protein + fat + veg + carbs) over high-GI foods
- Check ketones if glucose >14 mmol/L for >90 minutes despite corrections
Delivery and postpartum:
- Reduce insulin immediately after delivery: basal by ~50%, carb ratios back to pre-pregnancy levels
- If breastfeeding, may need further reductions (e.g., 1:10 → 1:12 or 1:15 carb ratio)
- Keep snacks readily available during feeds
- Expect insulin needs to shift again once milk supply is fully established
Guest
Professor Eleanor Scott is a consultant physician and one of the UK’s leading experts in pregnancy and maternal health in type 1 diabetes. She runs the pregnancy and diabetes service at Leeds Teaching Hospitals NHS Trust, leads a research group focused on pregnancy outcomes, and has shaped national and international policy on diabetes care in pregnancy. Professor Scott led the development and clinical trials of pregnancy-specific hybrid closed-loop technology and has published extensively on continuous glucose monitoring, automated insulin delivery, and improving outcomes for women with type 1 diabetes.
Disclaimer
The content available in The Glucose Never Lies® guides is for informational purposes only. Reading or listening to the content does not constitute medical advice and is not a substitute for individualized care, and does not create a clinician–patient or therapeutic relationship with The Glucose Never Lies® or any guest. Always discuss any changes to your diabetes management with your healthcare team. Pregnancy with type 1 diabetes requires specialist medical supervision — contact your diabetes team before, during, and after pregnancy.
Episodes on how to optimise lifestyle
- 7 — Fundamentals of The GNL
- 8 — Activity Snacking for TIR
- 18 — Exercise without fear
- 29 — 5 Principles of T1D Behaviour Change
- 32 — Menstrual cycle and T1D
