French Study Asks: How Much CGM Time Do Kids With Type 1 Diabetes Actually Need?

A study from France offers important insights for American families managing type 1 diabetes in children and teens — specifically around how often kids need to wear a continuous glucose monitor (CGM) to see meaningful health benefits.

What Researchers Studied

The Start-In! trial, conducted across multiple French pediatric diabetes centers, enrolled 151 children and adolescents between the ages of 2 and 17. All participants started with three months of full-time real-time CGM use. After that initial period, researchers randomly assigned them to one of three groups for the remaining nine months:

• Group 1: Return to traditional fingerstick blood glucose monitoring (no CGM)
• Group 2: Continuous CGM use — wearing the device at least 80% of the time
• Group 3: Intermittent CGM use — wearing the device roughly 40% of the time

The study's main goal was to see which strategy produced the best A1C results over 12 months. The average A1C at enrollment was 8.5% — equivalent to an estimated average blood glucose of approximately 197 mg/dL (converted from 69 mmol/mol).

What They Found

Surprisingly, no strategy came out on top. A1C levels changed at a similar rate across all three groups at the 3-, 6-, 9-, and 12-month checkpoints. Whether children wore the CGM full-time, part-time, or not at all after the initial three months, their long-term blood sugar control was statistically comparable.

However, there was one standout finding: severe hypoglycemia rates dropped significantly for the entire study population compared to the year before the study began. This benefit was seen regardless of which group children were assigned to — suggesting that even a short, structured period of CGM use may help reset dangerous low blood sugar patterns.

Children and caregivers across all age groups reported good tolerance of the CGM device and said they found it consistently usable. The French national health insurance system paid approximately €2,629 (roughly $2,800 USD) per patient for three months of full-time CGM use.

Why This Matters for US Patients

In the United States, the American Diabetes Association (ADA) recommends CGM for most children with type 1 diabetes and insurance coverage has expanded significantly — but CGM access remains inconsistent. This French research raises a nuanced and practical question: Is continuous, full-time CGM use always necessary, or can structured, strategic use deliver similar A1C outcomes?

For American families facing cost barriers, device fatigue, or insurance gaps, these findings are reassuring. They suggest that even intermittent CGM use — combined with strong educational support — may protect children from dangerous lows without sacrificing long-term glucose control. The authors specifically noted the need for improved patient and caregiver education, a priority equally relevant in the US where diabetes self-management education (DSME) programs are chronically underutilized.

The starting A1C of 8.5% in this French cohort closely mirrors national averages seen in American pediatric type 1 diabetes populations, making these results especially transferable.

The Bottom Line

Three months of consistent CGM use appears to deliver lasting protective benefits against severe hypoglycemia in children with type 1 diabetes — even if full-time use isn't maintained afterward. American families and clinicians can use this evidence to have more flexible, individualized conversations about CGM wear time without compromising safety.

Source: Guilmin-Crépon, Carel, Schroedt et al. "Is there an optimal strategy for real-time continuous glucose monitoring in pediatrics? A 12-month French multi-center, prospective, controlled randomized trial (Start-In!)." Pediatric Diabetes, 2019. PMID: 30663187. DOI: 10.1111/pedi.12820