BREAKING•Luna Diabetes closes $23.6M Series A led by Vensana Capital•FOUNDER FILE•John Sjölund - inventor on 30+ patents•Timesulin sold to Bigfoot, 2017•Bigfoot Unity acquired by Abbott, 2023•Built one of the first DIY closed-loop systems at a kitchen table in Stockholm• BREAKING•Luna Diabetes closes $23.6M Series A led by Vensana Capital•FOUNDER FILE•John Sjölund - inventor on 30+ patents•Timesulin sold to Bigfoot, 2017•Bigfoot Unity acquired by Abbott, 2023•Built one of the first DIY closed-loop systems at a kitchen table in Stockholm•

The Founder File

John Sjölund

The builder who keeps turning kitchen-table hacks into companies.

He sits in San Diego now, running Luna Diabetes, his third act in medtech. The first he sold to Bigfoot. The second he handed to Abbott. The third just raised $23.6 million to do one thing very, very well - automate insulin while you sleep.

CEO & Co-Founder Swedish-American 30+ Patents San Diego, CA

On The Record

John Sjölund - three companies, two exits, and a habit of building the thing nobody else thought small enough to bother with.

Dispatch / San Diego

He runs a 16-person company aimed at a problem the giants skipped.

Walk into Luna Diabetes and you will not find a hundred engineers chasing a moonshot. You will find a lean room - around sixteen people - pointed at one stubborn, unglamorous gap. Roughly nine in ten people who take insulin use a pen, not a pump. The automation revolution in diabetes care was built almost entirely for the pump minority. Sjölund's pitch is almost rude in its simplicity: so why not build automation for everyone else?

Luna's answer is a small wearable patch that handles dosing overnight - what Sjölund calls "sleep-only automation." It is not trying to be the device you wear and fuss over all day. It is trying to be the device you forget you are wearing by morning. That restraint is the whole strategy. When most founders are adding features, he is subtracting them.

In August 2025, investors agreed. Luna raised a $23.6 million Series A led by Vensana Capital, with the Swiss Diabetes Venture Fund, Winklevoss Capital and Ascensia Diabetes Care joining in. A pivotal clinical trial had already kicked off the previous October. The money goes where it always goes in regulated hardware: trials, submissions, and the unsexy machinery of actually manufacturing the thing.

$23.6M

Series A, Aug 2025

30+

Patents (lead / named)

Companies acquired

40+

Countries reached by Timesulin

Where the company's been

Sjölund's track record, by the numbers

Timesulin reach (countries)

40+

Series A raised

$23.6M

Patents

30+

Team size today

~16

Origin / Stockholm

It started at a kitchen table, after the kids were asleep.

Roughly a decade before Luna existed, Sjölund was sitting up at night in a Stockholm apartment, twin boys finally asleep, soldering together a system that did not yet have a market, a name, or anyone's permission to exist. He was among the first people in the world to build a working do-it-yourself automated insulin delivery loop - a homebrew rig that did what the medical-device industry had not yet shipped. He credits the open-source pioneer Dana Lewis for lighting the path.

This is the tell about how Sjölund works. He does not wait for the roadmap. He builds the crude version first, lives with it, and only then asks whether it could be a product. The kitchen-table rig became proof, and proof became conviction, and conviction is the thing that survives a decade of clinical trials and regulatory paperwork.

Before any of the medtech, he was somewhere else entirely: ad-tech. He cut his early teeth at Acceleration E-Marketing, bouncing between offices in Cape Town, New York and London. It is an unlikely launchpad for a man who would end up named on dozens of medical-device patents - and that is rather the point. He arrived at diabetes technology not as a credentialed insider but as a builder who could not leave the problem alone.

In 2010 he set up Patients Pending Ltd in London. Within a year, the first product had a name, a shape, and a brother attached to it.

The Family Business

His co-founder helped build Skype. Together they built a better cap.

In 2011, John launched Timesulin with his brother, Andreas Sjölund - one of the co-creators of Skype. While one brother had helped rewire how the planet makes phone calls, the two of them set out to fix something far smaller and, in its own way, far harder: the simple, nagging uncertainty of an insulin pen with no memory.

Timesulin was almost comically modest as a product. It was a replacement cap. You put it on your pen, and it quietly counted the time since you last used it. No app required to function, no screen to charge, no learning curve. It fit the most common insulin pens on the market, and it traveled - reaching users across more than 40 countries and becoming a best-seller at Diabetes UK.

2011

One small cap

A battery-powered replacement cap that timed itself. No prescription, no complexity - just an answer to a question pens couldn't answer on their own.

Downing Street

A handshake at No. 10

While building Timesulin, Sjölund met UK Prime Minister David Cameron at Downing Street - a plastic cap that earned a state-level audience.

2017

The first exit

Timesulin was acquired by Bigfoot Biomedical. Sjölund served as CEO right up to the sale, then went inside to build something bigger.

Act Two / Bigfoot

Inside Bigfoot, he built Unity. Abbott bought it.

Selling Timesulin did not mean cashing out. Sjölund joined Bigfoot Biomedical and formed the team behind Bigfoot Unity, a connected injection and dosing system that brought smart, recommendation-driven guidance to people using pens. It was the same instinct as Timesulin, scaled up: take the device millions already carry, and make it quietly smarter.

In 2023, Abbott Diabetes Care acquired Bigfoot Unity. That made two products Sjölund had shepherded from idea to acquisition - the second by one of the largest names in the field. Most builders would frame that as the finish line. He treated it as a runway.

2017 - Joins Bigfoot Biomedical after the Timesulin sale.

Unity - Forms and leads the team behind the connected dosing system for pen users.

2023 - Abbott Diabetes Care acquires Bigfoot Unity.

2020 - Already co-founding Luna with Jon Brilliant and Sean Saint.

The Founding Trio

He didn't build Luna alone - he built it with rivals turned partners.

Luna Diabetes was founded in 2020 by three people who had each already left a mark on the field. Alongside Sjölund sit Jon Brilliant, the company's CFO and a co-founder of Welldoc - the team behind BlueStar, the first FDA-cleared prescribable mobile health app for diabetes - and Sean Saint, an early Dexcom engineer who went on to lead Companion Medical and its InPen system. Three founders, three separate track records, and a shared frustration that the same gap kept going unaddressed.

What binds them is not a single resume but a single conviction: the people who use insulin pens have been treated as an afterthought in the automation era. Each founder had spent years close enough to the problem to be impatient with it. Luna is the attempt to stop circling and start building.

It is a pattern worth noticing in Sjölund's career. He keeps assembling teams from people who have already shipped hard things and already cashed out once. They do not need the next paycheck. They are there because the problem is interesting and unfinished - and because, between them, they have built nearly every adjacent piece of the puzzle already.

That is the quiet bet under Luna's lean headcount. A small room of people who have done this before can move faster than a large one learning on the job. The Series A investors - Vensana, the Swiss Diabetes Venture Fund, Winklevoss Capital, Ascensia - bought the team as much as the patch.

The Long Game

One problem, three companies, fifteen years.

2010

Founds Patients Pending Ltd in London to develop diabetes self-management products.

2011

Launches Timesulin with his brother Andreas Sjölund, a co-creator of Skype.

2012

Named one of Sweden's Ten Outstanding Young People; recognized as a Young Person of the Year.

2017

Timesulin acquired by Bigfoot Biomedical; joins the company and builds the Unity system.

2020

Co-founds Luna Diabetes with Jon Brilliant and Sean Saint.

2023

Bigfoot Unity acquired by Abbott Diabetes Care.

2024

Luna launches its pivotal clinical trial for an automated delivery system built for pen users.

2025

Luna raises a $23.6M Series A led by Vensana Capital.

The Method

His rule: don't build more technology. Build the right technology.

Restraint

Subtract, don't stack

Sjölund argues meaningful innovation rarely means a more complex device. It means a sharper definition of the problem and the discipline to solve only that.

Scope

Match the fix to the gap

"Sleep-only automation" is a deliberate narrowing. Not everyone wants a device managing them around the clock - so Luna handles the hardest hours and gets out of the way.

Signal

Clarity over data

On AI, his line is blunt: more data doesn't automatically mean better understanding. He wants intelligent systems that reduce cognitive load, not add to it.

The Margins

Five things that don't fit in a pitch deck.

The Skype connection. His Timesulin co-founder and brother, Andreas, was a co-creator of Skype. Big-tech pedigree, applied to a plastic cap.

Early to the timeline. He joined Twitter/X back in March 2009 - years before he founded any of his diabetes companies.

Three cities, one mission. He has built companies from Stockholm, London and now San Diego, and answers to both a Swedish and an American passport.

Came in sideways. He started in advertising technology, not medicine - proof you don't need the credential to chase the problem.

Decorated young. Sweden named him one of its Ten Outstanding Young People in 2012, and the UK's NHS honored his work for patient-developed innovation.