Glucose has specific frequencies at which it absorbs NIR depending on the C-C, C-H, O-H bonds. Although, glucose absorbs radiation principally in the mid infra red range there is also some absorption due to overtones of absorption frequencies in the near infra red range.

Infrared radiation induces molecular vibrations as a result of which different bonds absorb light at different frequencies. Glucose for example is a hydrocarbon which consists of C-H, O-H, C-C, C=O functional groups which absorb photons with the right energy to excite overtone and combinations of fundamental molecular vibrations. Therefore, glucose is capable of absorbing NIR light. However, NIR absorption features are low in magnitude and highly overlapping in nature.

References

https://ir.uiowa.edu/etd/4901/

Article Selection of the most informative near infrared spectroscopy...

Hope that helps. Best of luck!!