Remember when your mom yelled at you for doing something dumb as a teenager, and it turned out she was right? That's basically the story of how I ended up in the emergency room with ketoacidosis back in 2004, thanks to a low-carb diet that went spectacularly wrong. Fast forward 22 years, and Abbott has just gotten FDA authorization for the Libre Duo, a continuous glucose monitor that also tracks ketones - probably because the universe has a sense of humor and wants to make sure I never forget my teenage mistakes.
The Libre Duo is the first 2-in-1 CGM that measures both glucose and ketone levels, which is a big deal for diabetics who live in constant fear of diabetic ketoacidosis (DKA). That's the condition where your body runs out of insulin, starts burning fat like a desperate college student, and produces ketones that turn your blood acidic. It's the leading cause of hospitalization for diabetics and has been increasing rapidly over the last decade, according to Marc Taub, vice president of technical operations for Abbott's diabetes care business. He calls the new sensor a "check engine light" for your body, which is a nice way of saying it'll yell at you before you keel over.
The sensor measures beta-hydroxybutyrate, a type of ketone, and is worn for 10 days at a time. It monitors ketones in the background and alerts users when they're approaching dangerous levels, just like CGMs do for glucose. It uses the same app, works with smartwatches, and lets caregivers monitor loved ones - a potentially huge benefit, since DKA is a significant risk for diabetic children. Dr. David Ahn, chief of diabetes at the Mary and Dick Allen Diabetes Center for Hoag Hospital, notes that ketone monitoring is more common in pediatric diabetes education, but adults rarely get the strips. "In a perfect world, [ketone strips] would be one of the things that we send patients home with," he says, "but in practical scenarios, it often just isn’t a top priority."
Ahn also points out two scenarios where ketone monitoring could be a lifesaver. First, insulin pump users face a higher risk of DKA because pump issues like leaks or connectivity problems can interrupt insulin supply. Second, diabetics taking SGLT2 inhibitors - a class of oral meds that help lower blood sugar by excreting excess glucose in urine - can have "euglycemic DKA," where blood sugar isn't high, but you're still in raging ketoacidosis. This has been a major reason the FDA hasn't approved SGLT2 inhibitors for Type 1 diabetics, despite their potential benefits. A 2-in-1 monitor could act as a fail-safe, potentially opening up new treatment options.
But hold your horses - CGMs are not perfect. Diabetic subreddits are full of folks who appreciate the peace of mind but worry about accuracy, data fatigue, and what the heck their glucose levels actually mean. Type 1 diabetics discussing the Libre Duo have mixed feelings: some say they haven't needed ketone checks in over a decade, while others fear false positives causing disruptive alerts. (And as someone who's been testing the Dexcom G7, those alerts can be really loud.)
Ahn is cautiously optimistic: "I think it’s going to maybe be a rocky first year, or couple of years, but I’m also excited because I think we’re going to learn a lot. There’s so much we don’t know about ketone levels on a continuous basis." He points out that even a ketone strip doesn't give a number - just a color code of mild, moderate, or severe. So we're venturing into uncharted territory, and the medical community is "a little anxious about understanding the signal-to-noise ratio." Expect false positives.
Abbott worked with the FDA and clinicians to set ketone performance standards for the Duo, but even experts admit there's guesswork. A recent consensus statement set a cutoff of 3 mmol/L, but as Ahn says, "that’s our best guess as to what numbers we should start worrying about." Factors like pregnancy, illness, fasting, and heavy exercise can temporarily raise ketone levels, muddying the waters further.
Eventually, this tech will probably follow the familiar wearable script: it'll help the medical community learn a ton about ketones and DKA, but the early stages will be bumpy. For now, the Duo requires a prescription, and Abbott has no immediate plans for over-the-counter sales. But you don't have to be a genius to see where this is heading. Metabolic tech is the new wearable frontier - GLP-1s are all the rage, the keto diet has been popular for two decades, and health startups are dying to measure your bodily fluids. It's not hard to imagine wellness influencers turning the Duo into a "secret hack" the medical establishment doesn't want you to know about. That's exactly what happened with CGMs.
Reflecting on my own ER trip, I wonder if a gadget like this would have saved teenage me. The self-quantifying nerd says yes. The wearable expert suspects I'd have spiraled into data obsession and fatigue instead. Either way, the Libre Duo is a neutral tool - it has the potential for good, but it requires thought and discernment. Most people won't need to monitor for ketoacidosis, so when medical science adds another data set to our lives, we should ask why. What does it actually tell us, and not just what we hope it says?