This study aimed to evaluate whether insulin elevation affects superficial dermal microcirculatory blood flow and near-infrared diffuse reflectance spectral signals within the 1050–1609 nm wavelength range. To separate insulin-related effects from blood glucose-related effects， a whey protein load experiment was designed and compared with a glucose load experiment. By combining serum insulin measurement， laser Doppler flowmetry， and near-infrared diffuse reflectance spectroscopy， this study investigated whether insulin-induced superficial dermal perfusion changes could be detected optically and whether they should be considered a major physiological interference source in noninvasive blood glucose measurement.Six healthy volunteers were enrolled in the load experiments. Each subject ingested 100 mL of aqueous solution containing either 20 g glucose or 20 g whey protein. The glucose load was used to induce blood glucose elevation accompanied by insulin secretion， whereas the whey protein load was used to stimulate insulin secretion while minimizing blood glucose fluctuation. Near-infrared diffuse reflectance spectra were collected from the skin during both load conditions to monitor local optical responses in the superficial dermal region. Signals were acquired at six selected wavelengths： 1050， 1219， 1314， 1409， 1550， and 1609 nm， covering optical information related to hemoglobin， lipid， water， glucose， and tissue scattering. Among them， 1050 nm was considered relatively sensitive to hemoglobin absorption， while 1550 nm was regarded as the most sensitive wavelength for glucose-related spectral changes in this study. Differential absorbance was used as the main spectral feature. The spectral responses after glucose and whey protein loading were compared to determine whether insulin-related perfusion changes could produce distinguishable optical variations. In two of the six subjects， venous blood samples were collected at ingestion and 30 min after ingestion in both load experiments， and serum insulin concentration was measured by biochemical analysis. In the same two subjects， superficial dermal microcirculatory blood flow was monitored using laser Doppler flowmetry. The measurement depth of LDF was approximately 1 mm， mainly corresponding to the superficial dermis and the region near the subpapillary vascular plexus. The LDF signal was used to evaluate local microcirculatory perfusion because it reflects the combined contribution of moving red blood cell concentration and mean velocity within the sampling volume. In addition， the differential absorbance changes within 30 min after ingestion were statistically compared between the two load conditions.Serum insulin measurements showed that both glucose loading and whey protein loading clearly stimulated insulin secretion in the monitored subjects， indicating that the whey protein intervention successfully produced an insulin-elevating condition. However， LDF results showed that the superficial dermal microcirculatory blood flow signals did not change obviously during either load condition. The changes in LDF-related parameters were small during both experiments， and their magnitudes were comparable. This suggests that insulin elevation induced by the two interventions had a limited influence on superficial dermal microcirculatory perfusion under the present experimental conditions. The near-infrared spectral responses showed clear differences between the two load experiments. After glucose ingestion， the spectral signals of all six subjects changed noticeably and showed a trend generally consistent with blood glucose variation. Among the six selected wavelengths， the differential absorbance at 1550 nm showed relatively good correlation with blood glucose changes， suggesting that this wavelength was more sensitive to glucose-related optical responses. By contrast， after whey protein ingestion， the overall spectral signals remained relatively stable， and no significant systematic spectral change was observed. The differential absorbance changes within 30 min after ingestion were significantly different between the glucose load and whey protein load conditions， with p < 0.05， indicating that the glucose-induced spectral response was significantly stronger than the whey protein-induced response. Although the overall spectral response after whey protein loading was weak， some subjects showed slightly increased spectral fluctuation compared with the fasting state. In particular， Subject 5 showed relatively obvious fluctuation in the 1050 nm differential absorbance signal. Since 1050 nm is relatively sensitive to hemoglobin absorption， this fluctuation may indicate a mild blood-related optical response or slight superficial microcirculatory variation after whey protein ingestion. However， compared with the glucose load experiment， the amplitude of spectral changes after whey protein ingestion was much smaller. Moreover， no stable or clearly distinguishable spectral variation was observed at 1550 nm after whey protein loading， although this wavelength showed the highest sensitivity to blood glucose variation during glucose loading. These results suggest that even if insulin-induced superficial dermal microcirculatory fluctuation exists， its influence on the collected 1050–1609 nm near-infrared spectral signals is limited and insufficient to generate a stable glucose-like spectral response. The results also indicate that the optical responses observed during glucose loading cannot be attributed mainly to insulin-related superficial dermal microcirculatory effects. Glucose loading may induce multiple physiological responses in addition to changes in blood glucose and insulin， including changes in cell size， local osmotic status， tissue metabolism， and other optical properties of skin tissue. Since this exploratory study included only six healthy subjects， and insulin concentration and LDF measurements were performed in only two subjects， the findings should be interpreted cautiously.Insulin elevation showed only a limited effect on superficial dermal microcirculatory blood flow and near-infrared diffuse reflectance spectral signals within the 1050–1609 nm range. Its influence was not sufficient to form a stable and distinguishable optical interference under the present experimental conditions.