Belgium Study: Advanced Insulin Pump Technology Shows Promise for Pregnant Women with Type 1 Diabetes

A study from Belgium has shed important light on one of the most challenging situations in diabetes care: managing type 1 diabetes (T1D) during pregnancy. Researchers at KU Leuven and UZ Leuven — two of Europe's leading academic medical centers — tested whether an advanced automated insulin delivery system could improve blood sugar control and safety for pregnant women with T1D. Their findings, published in The Lancet Diabetes & Endocrinology (2024), offer both encouragement and important nuance for patients and providers in the United States.

What the Researchers Did

The CRISTAL trial enrolled 95 pregnant women with type 1 diabetes across 12 hospitals in Belgium and the Netherlands. Women were randomly assigned either to use the MiniMed 780G — an advanced hybrid closed-loop (AHCL) system that automatically adjusts insulin delivery based on continuous glucose readings — or to continue with their standard insulin therapy. The study ran from early pregnancy (around 10 weeks gestation) through the third trimester, with blood sugar monitored continuously throughout.

The target blood glucose range used in this study was the pregnancy-specific standard: 63–140 mg/dL (converted from 3.5–7.8 mmol/L). For context, standard non-pregnancy targets in the US are typically 70–180 mg/dL — pregnancy demands much tighter control because elevated blood sugar poses serious risks to both mother and baby.

What They Found

The headline result was nuanced: overall, women using the MiniMed 780G did not spend significantly more time in the target blood sugar range compared to those on standard therapy (66.5% vs. 63.2%, a difference that was not statistically significant). However, the automated system delivered meaningful benefits in two critical areas:

• Nighttime glucose control improved significantly — women using the 780G spent about 6.6 more percentage points of overnight time within target range, meaning roughly an additional 47–48 minutes per night with safer blood sugar levels.
• Dangerous low blood sugar (hypoglycemia) was substantially reduced — time spent below 63 mg/dL (<3.5 mmol/L) dropped by 1.34 percentage points overall and 1.86 percentage points overnight. In pregnancy, nighttime lows are particularly dangerous and frightening for patients.
• Patient satisfaction was notably higher among women using the automated system, a factor that directly affects long-term adherence and mental health.

No unexpected safety events occurred with the MiniMed 780G during pregnancy.

Why This Matters for US Patients

Here's the critical point for American patients: the MiniMed 780G is not currently FDA-approved for use during pregnancy in the United States. Many US providers use it "off-label" or rely on older closed-loop systems. This Belgian trial — one of the first rigorous randomized controlled trials specifically designed for pregnant women with T1D — provides real-world safety and efficacy data that could support future FDA review and updated clinical guidelines.

The American Diabetes Association (ADA) and the American College of Obstetricians and Gynecologists (ACOG) both emphasize tight glucose control during pregnancy, recommending time-in-range goals similar to those used in this study. This Belgian research directly supports the case for using advanced automated insulin delivery to meet those goals more safely — especially overnight when manual management is most difficult.

If you are pregnant or planning a pregnancy with type 1 diabetes, talk to your endocrinologist about closed-loop insulin delivery options and ask specifically about the current evidence and any available clinical trials near you.

Citation

Benhalima K, Beunen K, Van Wilder N, et al. Comparing advanced hybrid closed loop therapy and standard insulin therapy in pregnant women with type 1 diabetes (CRISTAL): a parallel-group, open-label, randomised controlled trial. The Lancet Diabetes & Endocrinology. 2024. DOI: 10.1016/S2213-8587(24)00089-5. PMID: 38697182.