Diabetes: light-based skin scan can replace finger-prick glucose tests

For millions managing diabetes, the ritual of finger pricks is an unwelcome daily routine. Researchers at MIT are developing a needle-free alternative that reads blood glucose by shining light on the skin — a technique that could dramatically cut down on painful checks and improve long-term monitoring.

The team has built a bench-top device roughly the size of a shoebox and has already shrunk that prototype into smaller, wearable formats now entering early human testing. Their approach uses optical analysis to detect glucose signals noninvasively, producing results that align closely with current continuous glucose monitors that rely on subcutaneous sensors.

How near-infrared light and Raman spectroscopy detect glucose under the skin

The new system is built around a form of optical fingerprinting called Raman spectroscopy. In simple terms, the method illuminates tissue with near-infrared light and analyzes how molecules in the skin scatter that light. Each molecule shifts the light in a subtly different way, creating a spectral pattern that can be read like a chemical barcode.

Glucose produces a very faint Raman signal compared with the many other molecules in skin and interstitial fluid. The MIT team overcame that problem by changing how light enters and leaves the tissue: they illuminate the skin at one angle and collect the scattered light at a different angle. That geometry reduces background noise and makes the glucose signature far easier to identify.

Rather than recording a full spectrum made up of thousands of data points, the researchers discovered they could extract meaningful glucose readings by focusing on just a few spectral bands — one that reflects glucose plus two reference bands to account for background. This selective approach cuts down on hardware complexity and cost, allowing accurate measurements with a far smaller, cheaper instrument.

Clinical testing: shoebox device shows promise versus implanted sensors

Researchers evaluated the original device in a controlled clinical setting at the MIT Center for Clinical Translation Research. In one experiment, a healthy volunteer rested an arm on the instrument while the team recorded glucose readings roughly every five minutes; each scan took about 30 seconds to complete.

To provoke a meaningful change in blood sugar, the participant drank two 75-gram glucose beverages during the four-hour session. The optical device tracked rises and falls in glucose concentration and produced results that matched closely with two commercially available continuous glucose monitors worn simultaneously — devices that measure interstitial glucose with a sensor placed under the skin.

• Measurement cadence: readings taken every five minutes, ~30 seconds per scan
• Validation stimulus: two standardized 75-gram glucose drinks
• Comparative baseline: two invasive CGMs worn by the subject

Those early findings suggest the noninvasive technique can reach clinically useful accuracy levels, at least in the small study population tested so far.

Making it wearable: cellphone-sized prototype and plans for a watch-sized sensor

After the shoebox prototype, the team rapidly moved to miniaturized designs. A cellphone-sized unit is currently being trialed on healthy and prediabetic volunteers, and engineers are working to reduce the form factor to a watch-sized device.

What the next-generation devices aim to deliver

• Continuous, needle-free glucose tracking that avoids skin punctures.
• Reduced skin irritation compared with subcutaneous, sensor-based CGMs.
• Lower recurring cost because there’s no implanted sensor to replace every few weeks.

Researchers say the smaller prototypes retain the same optical approach used in the initial device while employing more compact optics and electronics so the monitor can be worn comfortably for extended periods. A larger clinical trial in partnership with a local hospital is planned for the coming year to include participants who have diabetes.

Benefits, obstacles, and what remains to be proven for noninvasive glucose monitors

Replacing finger sticks and implanted sensors with light-based monitoring could have broad public health benefits: better testing adherence, fewer skin infections and irritations, and easier daily life for people with diabetes. But technical and regulatory hurdles remain.

• Benefits:

  • Noninvasive: eliminates routine pricking and implanted leads.
  • Potentially lower long-term cost and waste from disposable sensors.
  • Fast measurements that can be taken frequently without discomfort.

• Challenges:

  • Robustness across diverse skin tones, ages, and body types must be confirmed.
  • Motion, ambient light, and sweat can introduce noise that needs compensation.
  • Regulatory validation requires large, multi-center trials comparing the device against clinical blood glucose references.

• Next technical steps: improving miniaturization, extending battery life, refining algorithms for calibration and drift correction, and ensuring consistent performance in real-world conditions.

The research team includes MIT postdoctoral researcher Arianna Bresci as lead author and MIT research scientist Jeon Woong Kang as the senior author. Their findings are published in the journal Analytical Chemistry and mark an important step toward a practical, noninvasive glucose monitor that could one day spare millions from routine finger pricks.

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Michael Thompson

Michael Thompson is an experienced journalist covering U.S. and global news. With ten years on the front lines, he breaks down political and economic stories that matter. His precise writing and keen attention to detail help you grasp the real‑world impact of every event.