Noninvasively monitoring insulin is crucial for advancing precision nutrition and promoting healthy living by enabling a deeper understanding of individual metabolic responses to dietary intake. Insulin is a key regulator of blood sugar and energy metabolism, and its dysregulation is linked to conditions such as diabetes, obesity, and metabolic syndrome. By noninvasively tracking insulin levels, individuals can gain real-time insights into how their body processes different foods, allowing for the personalization of diets to optimize metabolic health, manage weight, and reduce disease risk. This approach also empowers proactive lifestyle adjustments to maintain insulin sensitivity, improve glycemic control, and enhance overall well-being. Decentralized insulin quantification in biofluids, including saliva and serum, based on lateral flow assay or electrochemical sensor has been reported. However, these approaches have poor sensitivity and fail to quantify insulin with a high temporal resolution.