A Future Without Needles: Optical Glucose Monitoring for Diabetes
In an article in ‘Nature Metabolism’, Andreas L. Birkenfeld and Vasilis Ntziachristos discuss advances in non-invasive glucose monitoring for people with diabetes. Optical measurements through the skin are difficult because they often only show average values from different layers of the skin. A new study is using a special form of Raman spectroscopy to measure glucose levels directly in the cutaneous blood vessels. This could improve glucose monitoring in humans.
Continuous glucose monitoring (CGM) has revolutionized diabetes care. Today, people with diabetes can use these systems to continuously monitor their blood sugar without finger pricks. The devices use microneedles to measure glucose levels in the interstitial fluid, which is located between the cells. One disadvantage is the delayed glucose measurement because the glucose must first reach the interstitial fluid from the blood capillaries.
The next step is the development of non-invasive glucose measurement methods that do without needles. To this end, optical and optoacoustic methods are being investigated. One highly promising technology is Raman spectroscopy, which identifies molecules such as glucose based on their vibrations after interacting with light. Until now, it has been a problem that this method mixes signals from all skin layers, which impairs accuracy. Another key method that has already existed for a long time is the optoacoustic technology termed depth-gated mid-infrared optoacoustic sensor (DIROS)1. It enables blood sugar to be measured by time-gating optoacoustic signals so that only measurements in the capillary-rich subcutaneous layers are recorded.
Improved Raman Spectroscopy for Glucose Monitoring
A new study by Zhang et al. in Nature Metabolism 2 shows that Raman spectroscopy can be improved by focusing on vessel-rich layers of the skin. The researchers used multiple μ-spatially offset Raman spectroscopy (mμSORS). This method makes it possible to detect signals from deeper skin layers where the capillaries are located. The researchers compared the results of their method with the plasma glucose levels of 230 participants. The new technology demonstrated a high degree of accuracy and could represent a promising method for non-invasive glucose monitoring.
Further Challenges Must Be Resolved
The authors Birkenfeld and Ntziachristos point out that, despite the promising results, a number of challenges still need to be resolved before widespread use among people with diabetes is possible. The current measurement time of around eight minutes makes it difficult to capture rapid blood sugar fluctuations, which are important for precise hypoglycemia monitoring. In addition, the current device is as big as a desktop computer, which hinders use at home.
“Nevertheless, this technology is a step towards a needle-free future for glucose monitoring. On the whole, the mμSORS technology appears to be taking non-invasive glucose monitoring to the next level by providing a proof of concept for its applicability for people with and without diabetes,” says Prof. Andreas Birkenfeld. “Although some aspects need to be further optimized, such as accuracy in the hypoglycemic range, the measurement time, and the size of the device, the presented data are a convincing step towards a needle-free and non-invasive future for millions of patients.”
1Uluc, N. et al. Non-invasive measurements of blood glucose levels by time-gating mid-infrared optoacoustic signals. Nat Metab6, 678-686, doi:10.1038/s42255-024-01016-9 (2024).
2Zhang, Y., Zhang, L., Wang, L. et al. Subcutaneous depth-selective spectral imaging with mμSORS enables noninvasive glucose monitoring. Nat Metab (2025). https://doi.org/10.1038/s42255-025-01217-w
Original publication:
Birkenfeld, A.L., Ntziachristos, V.: A future without needles: non-invasive glucose measurements in patients with diabetes. Nat Metab (2025). https://doi.org/10.1038/s42255-025-01221-0
About the researchers:
Prof. Dr. med. Andreas Birkenfeld
Andreas Birkenfeld is the Medical Director and Chairman of the Department of Diabetology, Endocrinology and Nephrology at the University Clinic Tübingen as well as Director of the Institute for Diabetes Research and Metabolic Diseases (IDM), Helmholtz Munich. He is a member of the executive board and one of the five speakers of the German Center for Diabetes Research (DZD).
Prof. Vasilis Ntziachristos
Vasilis Ntziachristos is Director of the Institute of Biological and Medical Imaging as well as Director of the Bioengineering Center at Helmholtz Munich. He holds the Chair of Biological Imaging, Central Institute for Translational Cancer Research (TranslaTUM), School of Medicine and Health & School of Computation, Information and Technology, Technical University of Munich. He is the inventor of the DIROS technology1.
More information can be found at the DZD webpage.