Danjam Lab · Sleep cover for Dexcom G7

I got tired of pressure alarms waking me up, so I made this.

Danjam Guard is a rigid dome that sits over your CGM sensor. When you lie on your side, the dome takes the weight of the bed and passes it to the skin around the sensor, not onto it.

How to order Meet the maker
An arm lying on a quilt. A white Danjam Guard held by a khaki strap sits on the back of the upper arm and touches the bed first.
The maker's own arm. Lying on your side, the cover touches the bed before the sensor does.
  • Dexcom G7Designed for it
  • Cover + strap30 cm elastic hook-and-loop
  • Made in Korea3D printed, checked by hand
  • No tapePut on and take off alone

Danjam Lab is a tiny lab for better nights.

"Danjam" is Korean for deep, sweet sleep. We take the problems a type 1 diabetic runs into at night and solve them with things we make ourselves. Danjam Guard is the first one.

The lab
Run by one person, Mingyu Jo, in Daejeon, Korea. He is a type 1 diabetic who sleeps with a Dexcom G7 and a pharmacy student. Every cover is printed, checked and packed by hand.
The guard
A pressure-spreading sleep cover that sits over the Dexcom G7 sensor, held by an elastic strap. Two models today, A1 and A3. Versions for FreeStyle Libre and CareSens Air are in development.

04:12 AM

The alarm goes off. Your glucose is actually fine.

A CGM reads glucose from the fluid under your skin. When the sensor is squeezed, that fluid can't move freely, the reading drops, and the app sounds a low alarm. This is often called a compression low.

A 12-hour Dexcom G7 graph. Around 5 AM the reading briefly dips below 55 and then returns to about 100.
The maker's own Dexcom G7 night. Every dip meant getting up to check whether it was a real low or just pressure.
  1. The sensor on the back of your arm gets pressed into the mattress when you roll onto your side.
  2. The reading suddenly drops and the low alarm goes off.
  3. You check with a finger prick. It's normal. Getting back to sleep is the hard part.
  4. It happens again the next night, and whoever sleeps next to you wakes up too.

Designed so the cover gets pressed, not the sensor.

Cross-section of the cover worn on an arm, with blue arrows showing force travelling from the top of the dome down its walls to the skin beside the sensor.
Where the force goes. Pressure from the bed runs over the dome, down its walls and into the skin around the sensor.
A yellow cover turned upside down, showing the hollow space inside and the vent holes.
Inside the cover. The space for the sensor is left empty.
01

A rigid dome with a gap

The inside never touches the top of the sensor. As long as the dome holds its shape, no force reaches the sensor. That is why it is printed in rigid PLA, not a soft patch.

02

Vents for sweat

Holes in the top let heat and moisture out, so your adhesive patch holds up better overnight.

03

A strap you can do one-handed

An adjustment slot on one side, a fixed end on the other. No tape. Tighten it with one hand at night and pull it off in the morning.

Two models today, more devices soon.

Each set is one cover and one 30 cm elastic strap. The models differ in how the strap attaches and where the pressure is spread.

White Danjam Guard A3 with its strap attached through a metal loop

A3 Improved

The rim is cut away on both sides where the sensor needle sits, so pressure lands further from it. Our pick if compression alarms wake you often.

White Danjam Guard A1 with the strap sewn onto both sides

A1 Sewn-on strap

The original. The strap is stitched straight onto the cover and spreads force evenly.

In development

FreeStyle Libre and CareSens Air

Separate covers built to each sensor's own dimensions. They launch after wear testing with real users.

White Danjam Guard Yellow Danjam Guard held in a hand Black Danjam Guard resting on a palm

We also print in yellow and black. Available colors depend on the store.

A1 and A3 fit the Dexcom G7 only. They are made for bare skin on the upper arm. If your arm is much larger than 30 cm around, the strap may feel tight.

On in about a minute.

  1. 01

    Thread the strap up through the slot and close the hook-and-loop to make a big loop.

  2. 02

    With the fastener facing your body, slide the loop up your arm to the sensor.

  3. 03

    Peel the fastener with one hand and pull toward your body until it fits.

  4. 04

    Lift the cover slightly and set it over the sensor. Don't overtighten.

  5. 05

    In the morning, just open the fastener. Nothing to throw away.

Close-up of a white Danjam Guard worn over a sensor on the back of the arm

The maker

I sleep with a Dexcom too.

Hi, I'm Mingyu Jo. I run Danjam Lab from Daejeon, Korea, and I study pharmacy at Korea University Sejong Campus.

I got tired of waking up to compression alarms. The 3D printed covers I found overseas cost too much once shipping was added. So in January 2026 I started modelling my own, and it took five rounds of prototypes before I could sleep through the night.

Other people in the Korean type 1 community had the same problem, so I gave the first ten away and asked for feedback. What I learned from them became A1 and A3.

Danjam Guard is the first thing I've made while living with type 1 diabetes. I want to keep making tools that make this condition easier to live with, and one day help with the work of curing it.

Fingers threading the strap through the metal loop of a yellow prototype cover
An early yellow prototype.
A makerspace with 3D printers and workbenches
The makerspace where the first prototypes were printed.

How we got here

  • Started keeping records

    Collected my own overnight graphs and community posts to see how common compression alarms are.

  • Five rounds of prototypes

    Changed the dome height, vents and strap attachment, and slept in every version.

  • Ten covers given away

    Shared with members of a Korean type 1 diabetes community in exchange for feedback.

  • Utility model application filed

    Filed a provisional application in Korea for the pressure-spreading and strap design.

  • Store opened in Korea

    Started selling on Naver Smart Store under the name Danjam Lab.

  • Patent work under way

    Preparing a full patent application with a regional IP support program.

What's next

Until type 1 has a cure, better nights in the meantime.

Libre, CareSens, and beyond Korea

Covers for FreeStyle Libre and CareSens Air are being designed to each sensor's dimensions. We're also getting ready to ship to CGM users outside Korea.

Ondang, an app to lighten self-care

Separately from Danjam Guard, I lead a small team building Ondang, a data app for people with type 1 diabetes. The goal is less fatigue from watching your numbers every day.

Helping toward a cure

It's why I study pharmacy. I want to take part, as a patient and a researcher, in bringing work that stops the autoimmune attack and restores beta cells to the people who need it.

Before you order

Is it a medical device?

No. Danjam Guard is an accessory designed to spread pressure over the sensor while you sleep. It does not prevent hypoglycemia or improve sensor accuracy, and results depend on sensor position, body shape and how you sleep. It is not an official Dexcom accessory.

Which devices does it fit?

A1 and A3 fit the Dexcom G7 worn on the upper arm, and are meant to be worn on bare skin. FreeStyle Libre and CareSens Air versions are in development.

I can see fine lines on the surface.

Each cover is 3D printed one at a time, so you may see thin layer lines. They don't affect how it works. Every cover is checked and finished by hand before shipping.

My skin is sensitive.

The cover is PLA and the strap is elastic hook-and-loop. Stop using it if you notice any irritation. Keep the strap snug, not tight.

Do you ship outside Korea?

Not yet. International shipping is being prepared. For now the covers are sold through our store in Korea.

A white cover with its strap and several yellow covers resting on bubble wrap

Try it tonight.

Each cover is checked and wrapped in bubble wrap before it ships. Right now we sell A1 and A3 through Naver Smart Store in Korea. International shipping is coming soon.

Visit the Korean store