The U.S. Food and Drug Administration (FDA) has approved the first continuous blood sugar monitor for diabetics that doesn't need backup finger prick tests.

Abbott's FreeStyle Libre system measures glucose levels through a small sensor applied to the back of your upper arm. The sensor, which is the size of two stacked quarters, provides real-time glucose readings for up to 10 days, both day and night. The sensor can also read glucose levels through clothes.

The FreeStyle Libre system provides people with diabetes a real-time glucose result, an 8-hour historical trend, and a trend arrow showing the direction their glucose is going. The touch-screen reader holds up to 90 days of data, which allows people to track their glucose levels over time.

Current models require users to test a drop of blood twice daily to calibrate, or adjust, the monitor. The method is both uncomfortable and pricey for the patient, discouraging the daily monitoring of their blood sugar.

Abbott's device was approved for adults with Type 1 or Type 2 diabetes and should be available in pharmacies across the U.S. within months. The company did not disclose the price of the reader or the sensors.

Abbott's system can't be used with an insulin pump, at least for now.