People with diabetes can now get an early warning when a dangerous complication starts to build in their bodies.

The U.S. Food and Drug Administration (FDA) on Tuesday authorized the first wearable sensor that continuously tracks ketones—chemicals the body makes when it burns fat instead of sugar for fuel.

It is also the first device anywhere to monitor ketones and blood sugar at the same time, the FDA said.

When ketones climb too high, they can cause diabetic ketoacidosis, or DKA. The American Diabetes Association warns that DKA can worsen within hours and lead to coma or death if it goes untreated.

Hospital admissions for DKA have risen 55% over the past decade, according to Abbott, which makes the device.