LIbrelink works in the same way as the reader. The per minute readings are aggregated every 15 minutes into a single value and stored on the sensor for eight hours. The graph you see is only the last 15 minutes of data, plus the previous x hours of 15 minute aggregate readings. That's why Librelink and the reader show a line rather than the data points. It would highlight that if it was the first time you'd scanned in 8 hours it would only show 31 15-minute readings and the last 15 1-minute readings.