Privacy Policy

1. Controller

The controller responsible for data processing in GlucoMatch within the meaning of the GDPR is:

Digital-Workshop, owner: Mario Röder
Mautner Markhof Gasse 96/1/17
1110 Wien
Austria
Email: glucomatch@digital-workshop.at

2. The essentials first

GlucoMatch stores your meals, photos, blood glucose values and settings exclusively on your device. There is no user account, no sign-in and no transfer of your records to us — we do not operate a server for this app on which your data could be stored.

There are exactly four situations in which any data leaves your device at all — each is described individually below: (1) you have a meal photo analyzed by AI, (2) you connect your own Nightscout instance, (3) ads are served, (4) you take out the “Ad-free” subscription. Your blood glucose and insulin values never leave your device in the process — values are only retrieved from Nightscout, never sent to it.

GlucoMatch contains no analytics, tracking or statistics SDKs. We do not track usage or build profiles.

3. Data on your device

GlucoMatch stores the following data exclusively in your device's local storage:

• Meals: name, time, photo, tags, estimated and confirmed carbohydrates or bread units (BE), notes
• Health data relating to meals: blood glucose before the meal, blood glucose at the 3-hour check, self-entered insulin dose
• Settings: app language, preferred carbohydrate and blood glucose unit, grams per BE, timer duration, time blocks with target blood glucose, carbohydrate factor (CR) including its display format, and correction factor (ISF), chart settings
• Progress: streak, experience points and unlocked achievements

Meal photos are stored in the app's persistent file area so that they are not lost when the operating system clears its cache. They stay on the device and are only transferred for the carbohydrate estimate (see below).

Your API key for AI image analysis and your Nightscout API secret are stored separately in your operating system's secure key storage (Android Keystore).

You can remove this data completely at any time by uninstalling the app or clearing its data in the Android settings. Since it is stored only here, that really removes everything.

4. AI analysis of your meal photos

When you take or select a photo and start the analysis, the image — scaled down to at most 1024 pixels — is transferred to an AI service that estimates its carbohydrate content. Without this transfer, the photo estimate is technically not possible.

By default, Google's Gemini API is used for this (Google Ireland Limited / Google LLC, USA). In the settings you can choose OpenAI instead (OpenAI, L.L.C., USA) and also store your own API key there.

Only the image itself is transferred, together with the analysis instruction. No blood glucose or insulin values, no notes and no identifier that identifies you are sent. For quick-pick examples and saved meals from your memory, no AI request takes place at all — those values come from the app itself.

Please note that a meal photo may unintentionally contain further information, such as people in the background. Pay attention to what is in the picture when taking photos.

5. Nightscout connection (optional)

If you enter the address of your own Nightscout instance and your API secret in the settings, GlucoMatch retrieves your current glucose values from there. GlucoMatch only reads — no meals, insulin values or other entries are uploaded to your Nightscout instance.

This connection runs directly between your device and the server you specified. The data does not pass through our systems, and we have no access to it. You or your respective provider are responsible for the operation and data protection of your Nightscout instance. Your API secret is converted into a SHA-1 hash before transfer and never leaves your device in plain text.

6. Advertising

GlucoMatch is financed by ads from Google AdMob (Google Ireland Limited, Gordon House, Barrow Street, Dublin 4, Ireland): a slim ad banner on the start screen and occasional full-screen ads during the photo analysis. The first photo analyses after installation are ad-free. The “Ad-free” subscription (see next section) switches the ads off.

Google, as an independent controller, processes among other things your device's advertising ID, device and browser information and your truncated IP address in order to serve ads and measure their delivery. None of your health data and none of your photos are transmitted to Google, and your health data is not used to serve personalized ads.

Users in the European Economic Area and the United Kingdom are asked via a consent prompt from Google at first launch whether personalized ads may be shown. If you decline, only non-personalized or limited ads are served. You can change your decision at any time in the app settings under “Ad privacy options”.

You can reset or delete your advertising ID in the Android settings under “Privacy → Ads”. Information on data processing by Google can be found at policies.google.com/technologies/ads.

7. “Ad-free” subscription (optional)

You can switch off the ads in GlucoMatch with a paid subscription. Purchase, payment, renewal and cancellation are handled entirely by your device's app store: on Android by Google Play (Google Ireland Limited), on iOS by the App Store (Apple Distribution International Ltd., Hollyhill Industrial Estate, Hollyhill, Cork, Ireland). We receive neither payment data nor your name or email address; the respective store's privacy policy applies to the processing of the purchase.

To know whether ads may be shown, the app asks Google Play or the App Store at every start whether your subscription is active, and stores only that result (active or not active) locally on your device. We do not run a server for this and use no other service provider. With an active subscription, no more ads are shown, and from the next app start on the ad SDK is not started at all.

8. Permissions and notifications

• Camera: only to take a photo of the meal. You are asked only when you use the feature.
• Photos / media: only to select an existing image for the estimate. GlucoMatch does not read your gallery in the background.
• Notifications: for the reminder of the 3-hour check. These reminders are scheduled locally on your device; no data is transferred to a server for this.

9. Legal bases

• Blood glucose, insulin and meal data are health data within the meaning of Art. 9 GDPR. They are processed exclusively on your device; to the extent that any processing by us takes place at all, it is based on your explicit consent under Art. 9(2)(a) GDPR, which you give by entering these values and can withdraw at any time with effect for the future.
• AI image analysis and Nightscout connection: your consent, Art. 6(1)(a) GDPR, given by starting the analysis or activating the connection.
• Advertising: your consent, Art. 6(1)(a) GDPR, or legitimate interest in financing the app, Art. 6(1)(f) GDPR.
• “Ad-free” subscription: performance of the contract, Art. 6(1)(b) GDPR.

10. Transfers to third countries

The services used for image analysis, advertising and the subscription (Google, Apple, OpenAI) may process data in the USA or other countries outside the EU. Transfers are based on the European Commission's standard contractual clauses or, where the respective provider is certified, on the EU-U.S. Data Privacy Framework. A level of data protection equivalent to European law cannot be guaranteed in every case in third countries. This concerns only the meal photos, the advertising identifiers and the processing of the subscription purchase — your health values are not transferred.

11. Retention period

• Data on your device remains stored until you delete it in the app or uninstall the app.
• Images transferred to the AI services are subject to the retention periods of the respective provider; we do not store anything there permanently and keep no copies ourselves.

12. Deleting your data

There is no user account and no data stored with us whose deletion you would have to request. All your records are on your device.

You delete individual meals directly in the history. To remove everything, uninstall the app or clear its data in the Android settings under “Apps → GlucoMatch → Storage → Clear data”. This also removes the stored photos.

13. Your rights

You have the following rights towards the controller: access (Art. 15 GDPR), rectification (Art. 16), erasure (Art. 17), restriction of processing (Art. 18), data portability (Art. 20) and objection to processing (Art. 21). You can withdraw any consent you have given at any time with effect for the future; this does not affect the lawfulness of processing carried out before the withdrawal.

To exercise these rights, contact glucomatch@digital-workshop.at. Please note that we cannot provide information about your records because we do not have them — they are located exclusively on your device. Irrespective of this, you have the right to lodge a complaint with a data protection supervisory authority, in particular in the EU member state of your habitual residence or of the alleged infringement.

14. Children

GlucoMatch is intended for adults. Users under the age of 16 require the consent of their parents or legal guardians. We do not knowingly collect data from children without this consent.

15. Not a medical device

GlucoMatch is a food and history log, not a medical device, and has not been reviewed or approved by any authority. The app does not replace medical advice. This notice is not part of the data protection information but is provided for your safety.

16. Changes to this policy

This privacy policy is updated when the app or the legal situation changes. The version published here applies. Last updated: 6 October 2026.

This English version is a translation provided for convenience. In the event of any discrepancy, the German version (Datenschutzerklärung) prevails.