CGM Overpatches for Swimming, Surfing, and Water Activities

The first time I went swimming in Bali with my Dexcom, I was paranoid. Would the water rip it off? Would the adhesive fail in the humidity? Would I emerge from the ocean minus one expensive sensor?

After countless beach days, surf sessions, and pool swims across Southeast Asia, I’ve figured out what works. Here’s everything I know about keeping CGMs attached during water activities.

The Problem

CGM adhesives are designed for everyday life, not tropical beach vacations. They face challenges from:

• Saltwater weakening adhesive bonds
• Chlorine degrading adhesive
• Humidity preventing proper initial adhesion
• Sunscreen creating barrier under patches
• Sweat (constant in hot climates) loosening edges
• Physical activity creating stress on the sensor

Without protection, sensors can peel, shift, or fall off entirely. At $50-100+ per sensor, that’s an expensive problem.

Overpatch Options

Pre-Made Overpatches

These are specifically designed for CGM sensors.

My experience: GrifGrips and Skin Grip have worked best for me in high-humidity environments. The fabric breathes better than pure adhesive patches.

Medical Tape Options

For budget-friendly or emergency solutions:

DIY Combinations

What I’ve found works in tropical conditions:

1. Skin prep wipe before sensor application
2. Sensor applied to clean, dry skin
3. Allow to set for 30 minutes before activity
4. Overpatch applied over entire sensor
5. Edge seal with additional tape if needed

Application Tips for Humid Climates

Getting things to stick in 85% humidity requires extra effort.

Pre-Application Prep

1. Shower and dry completely before application
2. Use air conditioning to reduce skin moisture
3. Apply skin prep wipe and let dry fully (2-3 minutes)
4. Clean with alcohol if skin prep isn’t available
5. Avoid sunscreen on application area

During Application

1. Press firmly for 30-60 seconds
2. Smooth from center outward to eliminate bubbles
3. Don’t stretch the overpatch while applying
4. Secure edges with additional pressure

Post-Application

1. Wait 30 minutes before water activity
2. Apply additional edge tape if needed
3. Check edges after drying from water

Activity-Specific Advice

Swimming (Pool)

Challenge: Chlorine degrades adhesive over time

Solutions:

• Apply overpatch before swimming
• Rinse with fresh water immediately after
• Pat dry gently (don’t rub)
• Check edges after each swim

My experience: Pools are easier than ocean. Chlorine is harsh but predictable.

Swimming (Ocean)

Challenge: Saltwater plus waves plus sand

Solutions:

• Use waterproof overpatch plus edge tape
• Apply waterproof sunscreen around (not under) patch
• Rinse with fresh water immediately after
• Keep sensor on upper arm (less impact from waves)

My experience: Arm placement works better than abdomen for ocean swimming. Less stretching and pulling.

Surfing

Challenge: Extended water time plus physical stress

Solutions:

• Strongest adhesive setup you have
• Consider sensor placement away from paddle motion
• Accept that sensors may not last full 10 days
• Carry backup sensors

My experience: Surfing is the hardest on sensors. I budget for potentially shorter sensor life during surf trips.

Snorkeling

Challenge: Face-down position plus extended water exposure

Solutions:

• Back-of-arm placement avoids snorkel gear contact
• Pre-apply overpatch morning of activity
• Standard waterproofing usually sufficient

My experience: Snorkeling is pretty gentle on sensors. Regular overpatch usually works fine.

Diving

Challenge: Pressure changes, extended submersion

Important note: Check your CGM manufacturer guidelines about diving depth limits. Most CGMs are rated for shallow swimming, not scuba depths.

For shallow freediving/snorkeling:

• Standard waterproofing applies
• Monitor sensor readings after depth changes

Troubleshooting Common Problems

Problem: Edges Lifting

Causes:

• Moisture under adhesive
• Insufficient skin prep
• Physical stress on sensor

Solutions:

1. Dry the lifted edge completely
2. Apply skin prep to the skin under the lifted edge
3. Press down and add tape over the edge
4. Consider full overpatch if not already using one

Problem: Sensor Shifting

Causes:

• Adhesive failing
• Too much movement during application
• Placement in high-flex area

Solutions:

1. If caught early, can sometimes rescue with tape
2. If significant shift, sensor may need replacement
3. Future prevention: better initial adhesion

Problem: Skin Irritation Under Patches

Causes:

• Trapped moisture
• Adhesive sensitivity
• Bacterial/fungal growth in humid conditions

Solutions:

1. Use barrier wipes before sensor application
2. Choose breathable overpatch materials
3. Rotate sensor sites
4. Allow skin to fully dry before application
5. See doctor if irritation is severe

Product Recommendations by Activity Level

Casual Water Activities (Pool Lounging, Light Swimming)

• Basic overpatch (GrifGrips, Skin Grip)
• Skin prep wipe
• No additional tape usually needed

Moderate Water Activities (Regular Swimming, Snorkeling)

• Premium overpatch
• Skin prep wipe
• Edge tape for extra security
• Post-activity inspection

Intense Water Activities (Surfing, Water Sports)

• Double coverage (original adhesive + full overpatch)
• Skin prep wipe
• Edge tape on all sides
• Backup sensor packed
• Accept potential shorter sensor life

My Travel Kit for Water Activities

Cost Considerations

Keeping CGMs attached during water activities adds cost:

Worth it compared to losing a $75+ sensor.

My Honest Take

I’ve lost exactly two sensors to ocean activities in three years. Both times were my fault for not using overpatches when I knew I should have. One came off during a surf session in Bali, the other peeled off in the waves in Koh Samui.

Two sensors at $75 each equals $150 in lessons learned. Now I overpatch everything, every time, even if I’m just going for a quick swim. The five minutes of prep is worth not watching $75 float away into the Andaman Sea.

You don’t have to skip the beach or the pool or the surf. You just have to respect that these sensors weren’t designed for what we’re putting them through, and plan accordingly.

Heading to Southeast Asia for beach time? Join our waitlist and ensure you have all the supplies you need.