The future of continuous glucose monitors is set to become more complex.

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I remember my mom as a dramatic figure, often prone to overreactions. During my teenage years, I once told her she needed to take a few chill pills. More often than not, I was right. But back in 2004, when she was swearing in Korean and speeding down the highway in a Honda Odyssey, swerving through traffic while I was battling nausea in the backseat, I had to admit she was justified in rushing me to the emergency room.

After two days of relentless vomiting, I thought I was just dealing with a nasty stomach bug. However, doctors were concerned when I couldn’t even keep down small sips of water. They asked if I was diabetic, to which my mom replied no, explaining I was just on a crazy low-carb diet. Dazed and confused, I was instructed to pee on a test strip, which changed color. Things went hazy after that as they hurried to get me into a bed. I don’t recall much else until I woke up hours later, two IV drips in, to a doctor explaining to my mom why unsupervised diets in teens can be dangerous.

In my misguided attempt to shed some pounds, I had inadvertently triggered a situation where the ketones in my blood reached toxic levels — a condition known as ketoacidosis.

This memory resurfaced when I learned that Abbott received FDA approval for a new continuous glucose monitor (CGM). The Libre Duo is the first 2-in-1 CGM that tracks both glucose and ketone levels. For diabetics, knowing about ketones is crucial, as it relates directly to ketoacidosis — the very reason I ended up in the ER nearly 22 years ago.

Ketoacidosis is a serious concern for diabetics. It occurs when there isn’t enough insulin to convert blood glucose into energy, leading the liver to burn fat instead, producing ketones as a byproduct. While ketones aren’t inherently harmful, excessive levels can make the blood dangerously acidic. This process can escalate quickly in diabetics and can be life-threatening if not addressed. It’s primarily a concern for Type 1 diabetics, who lack sufficient insulin, but it can also affect those with Type 2 diabetes, which often develops due to lifestyle factors.

“It’s actually the most common hyperglycemic emergency for people living with diabetes. It’s the leading cause of hospitalization, and it’s increased quite rapidly over the last decade,” says a diabetes care expert. “The symptoms of rising ketones are easily missed — they resemble flu or infection symptoms.”

According to the expert, the new Abbott sensor measures beta-hydroxybutyrate, a type of ketone, and is designed to act like a “check engine light.” Worn for 10 days, the sensor can alert users when glucose or ketone levels are out of range. This system aims to provide actionable warnings in a familiar format for diabetics, integrating with existing apps and smartwatches, allowing caregivers to monitor their loved ones’ levels — a significant advantage, especially for diabetic children.

“DKA is one of the primary fears or dangers of uncontrolled or unmonitored diabetes,” notes a diabetes specialist. He points out that ketone monitoring is more common in children as part of standard diabetes education. “Most adult clinicians, even endocrinologists, don’t routinely prescribe ketone strips … ideally, they would be included in patient care, but in practice, they often aren’t prioritized.”

The specialist also highlights two scenarios where ketone monitoring could be particularly beneficial. First, insulin pump users are at a higher risk of DKA due to potential undetected issues with their pumps, which could disrupt insulin delivery and lead to ketoacidosis. Second, diabetics on SGLT2 inhibitors — medications that help lower blood sugar by promoting glucose excretion in urine — could also benefit.

“SGLT2 inhibitors are quite common, primarily for Type 2 diabetes,” he explains, noting that they can also help Type 1 diabetics. “The challenge is that high blood sugar is our main indicator of DKA. With SGLT2 inhibitors, blood sugar might not be elevated, but ketoacidosis can still occur.”

This discrepancy is a key reason the FDA has yet to approve SGLT2 inhibitors for Type 1 diabetics, despite their potential to help manage blood sugar. Thus, a 2-in-1 glucose and ketone monitor could serve as a safety net, opening new treatment avenues for Type 1 diabetics. This, along with aiding diabetic children and insulin pump users, makes this technology seem like a no-brainer, right?

Well, it’s a bit more complicated than that.

CGMs are not without their flaws. A quick look at diabetic forums reveals users who appreciate the peace of mind CGMs offer but also express concerns about accuracy, data overload, and interpreting glucose readings. Discussions around the Libre Duo show that many Type 1 diabetics are skeptical. Some claim they haven’t needed to check for ketones in years, while others worry about false positives leading to unnecessary alerts.

“I think the first year or two might be a bit rocky, but I’m excited because we’ll learn a lot. There’s so much we don’t know about continuous ketone levels,” the specialist says. “A ketone strip typically doesn’t provide a number; it just indicates mild, moderate, or severe.”

This situation illustrates the double-edged nature of wearable technology. On one hand, it offers a broader understanding of bodily functions in various scenarios that were previously unmeasurable, potentially aiding medical discoveries. On the other hand, the challenge lies in filtering through the vast amounts of data to highlight the most relevant signals.

Abbott’s team collaborated with the FDA and clinicians to establish performance standards for the Duo. However, even among professionals, interpreting new data can involve a degree of uncertainty.

“There was a recent consensus statement from leading experts outlining guidance on ketone monitoring, setting a cutoff at 3 mmol/L. But even that is our best guess for when to start worrying,” the specialist explains. He adds that factors like pregnancy, illness, fasting, and intense exercise can also temporarily elevate ketone levels.

“The medical community is a bit anxious about understanding the signal-to-noise ratio,” he admits. “I anticipate there will be many false positives.”

In time, the Duo sensor will likely follow a familiar trajectory for wearables. It will undoubtedly enhance the medical community’s understanding of ketones and DKA. The initial phase may be bumpy, especially given the complex relationship between wearable tech and accuracy. For now, the Duo requires a prescription, and Abbott has no immediate plans for over-the-counter availability. However, it’s easy to envision a future where the Duo’s technology is marketed to a broader audience.

Metabolic technology is the new frontier in wearables. Health tech startups are increasingly interested in bodily fluids to measure metabolism. GLP-1 medications are gaining popularity, and the public is exploring gray market peptides. The keto diet, which focuses on achieving ketosis through fat-burning, has been trendy for nearly two decades. It’s not hard to see how various consumer wearable companies might view the Duo as a new revenue opportunity. From there, it’s easy to imagine wellness influencers promoting this technology as a “secret hack” that the medical establishment doesn’t want you to know about.

This is reminiscent of what happened with CGMs.

The Duo makes me reflect on my past mistakes. I ended up in the ER with ketoacidosis, a rare occurrence for non-diabetics, because I was a stressed-out teen drawn into a fad diet by glossy magazines and celebrities. Would a version of the Duo have helped me avoid that situation? The data enthusiast in me thinks so. However, the wearable tech expert in me suspects that, based on my previous experiences with CGMs, I might have spiraled into data obsession and fatigue instead of avoiding the ER.

This isn’t to say the Libre Duo is a bad product. Wearable tech is a neutral tool with the potential for significant benefits — it just requires careful consideration to be used healthily. The reality is that most people won’t need to monitor for ketoacidosis in their daily lives. When medical science introduces new data into our lives, it’s crucial to ask why; to understand what it truly conveys, rather than what we hope it means or what we wish it could do for us.