Why CGM Use Drops in Summer (And How to Fix It)

What This Study Found

Researchers followed 108 young adults with type 1 diabetes for an average of three years, collecting more than 22 million blood glucose readings. They wanted to understand when people were actually wearing their continuous glucose monitors (CGMs) — and when they weren't. What they found was a clear pattern: CGM use dropped in the warmer months (May through July), on weekends, and overnight. Only about half of participants (52.7%) wore their CGM consistently enough to get the full benefit.

Why This Matters If You Have Diabetes

A CGM only works when you're wearing it. Missing hours — or whole days — means missing glucose trends that could help you avoid dangerous highs and lows. The times people were most likely to skip their CGM (summer, weekends, nighttime) are often the times routines are most unpredictable. That's exactly when steady glucose data matters most.

This isn't about willpower. The study identified real, practical reasons people interrupted their CGM use:

• Insurance coverage changes — gaps in supply between plan changes or reauthorizations
• Sensor adhesive problems — sensors falling off, especially in heat, during swimming, or with active sweating
• Life transitions — starting college, moving, changing jobs
• Shorter sensor lifespan than expected

The Summer Problem Is Real

If you've ever had a sensor peel off at the beach or during a sweaty workout, you're not alone. Warm weather makes adhesion harder, and summer routines are less structured. The study confirmed that May through July were the months with the most disrupted CGM use — while January and December (when routines tend to be more settled) showed the most consistent wear.

Nights and Weekends: The Hidden Gaps

The data also showed a clear dip in CGM use on Friday through Sunday and between 7 PM and 5 AM. Overnight lows are among the most dangerous hypoglycemic events — so nighttime is one of the worst times to be without glucose monitoring. If you find yourself removing your sensor before bed because of discomfort or adhesive issues, that's worth solving.

What You Can Do About It

The good news: most of these barriers are fixable with the right supplies and a little planning.

• Use an adhesive patch or overtape during summer, exercise, or swimming to keep sensors secure longer
• Set a sensor replacement reminder so you're never caught without a fresh one
• Keep a backup supply on hand to bridge any insurance gaps or shipping delays
• Build sensor changes into your weekly routine — the study found weekday habits were more consistent, so use that to your advantage

Small habits around CGM supply management can make a real difference in how much usable data you get — and how well you can manage your glucose over time.

Citation

Cui, Stanger, Prioleau (2025). Seasonal, weekly, and individual variations in long-term use of wearable medical devices for diabetes management. Scientific Reports. PMID: 40251386. DOI: 10.1038/s41598-025-98276-6