In-depth correlation analysis between tear glucose and blood glucose using a wireless smart contact lens
Nature Communications volume 15, Article number: 2828 (2024 ) Cite this article
Tears have emerged as a promising alternative to blood for diagnosing diabetes. Despite increasing attempts to measure tear glucose using smart contact lenses, the controversy surrounding the correlation between tear glucose and blood glucose still limits the clinical usage of tears. Herein, we present an in-depth investigation of the correlation between tear glucose and blood glucose using a wireless and soft smart contact lens for continuous monitoring of tear glucose. This smart contact lens is capable of quantitatively monitoring the tear glucose levels in basal tears excluding the effect of reflex tears which might weaken the relationship with blood glucose. Furthermore, this smart contact lens can provide an unprecedented level of continuous tear glucose data acquisition at sub-minute intervals. These advantages allow the precise estimation of lag time, enabling the establishment of the concept called ‘personalized lag time’. This demonstration considers individual differences and is successfully applied to both non-diabetic and diabetic humans, as well as in animal models, resulting in a high correlation.
Continuous monitoring of biomedical signals in the human body is imperative for the diagnosis and management of metabolic disorders. With the development of wearable electronics, extensive efforts have been made to monitor diverse physiological signs through physical parameters (e.g., blood pressure, heart rate, electrocardiogram) and metabolites (e.g., glucose, amino acid, vitamins) over the past decade1,2,3,4,5,6,7,8,9. Among various metabolites, glucose is a significant biomarker for the diagnosis and management of diabetes, but it fluctuates drastically depending on the patient’s diet and lifestyle. Thus, continuous glycemic control is important to prevent the microvascular complications10, e.g., neurological, retinal, and renal complications, that can occur with diabetes. However, the measurement of glucose by a glucometer involves invasive blood sampling, and it has the limitation of single-time-point measurements, making compact glycemic management impossible. To overcome this limitation, the continuous measurement of glucose has been conducted with various body fluids, e.g., tears11,12, sweat13,14, saliva15, and interstitial fluid (ISF)16,17.
