The archive · Health & Care · Product decision · 2025-2026
Lucis bets prevention replaces waiting: $28M for biomarker tests plus an AI companion
Paris 2025-founded Lucis raised a $20M Series A months after seed; 10,000+ users and 1M+ biomarker tests as it bets prevention becomes the norm
Lucis
What the business is
A Paris preventive-health platform that analyzes 110+ blood biomarkers and turns results into physician-reviewed, AI-personalized health guidance.
Starting capital：EUR 24M total ($28M): EUR 7.2M seed Dec 2025; $20M Series A May 2026 (Singular-led)
How it started
Founded 2025 in Paris by Maxime Berthelot and Baptiste Debever, out of Y Combinator's 2025 batch. Both cite late-stage diagnosis as the failure to fix: the science exists, but the system acts only after symptoms appear.
What happened
Seed of EUR 7.2M closed Dec 2025 with Y Combinator and General Catalyst; Series A of $20M led by Singular in May 2026 with GC, YC and angels. By then Lucis had 10,000+ users in France, UK, Ireland and Portugal, 1M+ biomarker tests, lab partnerships with Eurofins and Randox, and a 20-person team.
No ending yet — it is still running.
Background
Lucis is a Paris preventive-health startup founded in 2025 by Maxime Berthelot and Baptiste Debever, both alumni of Y Combinator's 2025 batch. It sells a blood-biomarker test plus an AI health companion: the platform analyzes more than 110 biomarkers covering metabolic health, hormones, cardiovascular risk, inflammation and nutrients, then turns results into physician-reviewed, personalized recommendations on nutrition, supplements, lifestyle and follow-up testing.
The bet is that prevention can become the default in European healthcare. The founders argue the system acts only after symptoms appear, while the science to intervene earlier already exists. Lucis claims 99.9% of its initial users had at least one biomarker outside the optimal range without knowing it, which is exactly the gap it is trying to productize.
Money moved fast: a EUR 7.2M seed in December 2025 with Y Combinator and General Catalyst, then a $20M Series A in May 2026 led by Singular, bringing total funding to about EUR 24M ($28M). By then Lucis reported more than 10,000 users in France, the UK, Ireland and Portugal, over one million biomarker tests, lab partnerships with Eurofins and Randox, and a 20-person team.
Early engagement numbers are company-reported but suggestive: among users who completed a six-month follow-up, 75% improved at least three biomarkers without medication, and more than 80% opted to retest. Expansion into Spain, Germany and Italy is planned by the end of 2026. Lucis is still scaling and has no outcome yet.
What has to be true
- Late-stage diagnosis is the industry failure everyone already believes in; Lucis sells the earlier action point instead of arguing with the model.
- Blood biomarkers are objective, repeatable data - unlike wearables or self-reports - so a single test creates a natural reason to come back and retest.
- AI review plus physicians hedges both trust problems: consumers get personalization, skeptics get clinical oversight.
- The retest loop (80%+) is a subscription-like moat: each new test deepens longitudinal data that competitors cannot copy quickly.
What can be applied
When a category is 'wait until sick,' the wedge is a test plus a feedback loop that proves value - retest behavior (80%+) is the retention metric to optimize, not app usage.
Aftermath
As of late May 2026, Lucis is scaling: it counts 10,000+ users across France, the UK, Ireland and Portugal, has run more than one million biomarker tests, and is expanding into Spain, Germany and Italy by the end of 2026. It maintains a medical board and a network of 10+ physicians for clinical oversight, and its 20-person team is building out the AI companion app. No exit or public valuation has been reported; engagement metrics (75% of six-month follow-ups improving at least three biomarkers, 80%+ retest) remain company-reported.
Sources
- YC-backed French preventive health platform Lucis raises EUR 17.3 million Series A led by Singular
- Paris preventive health startup Lucis raises $20 million Series A four months after seed round to expand across Europe
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