Abstract: A main requirement for cells to function normally is the availability of glucose. Glucose, available either direct from circulation or storage, is converted to the essential energy that cells need to drive critical intrinsic functions. If cells are deprived of glucose, they become dysfunctional and suffer distress. Photobiomodulation, the use of specific wavelengths of light on body tissues, has been shown to promote, through small organelles called mitochondria, the metabolism of glucose to make energy for cells; this energy can be used to improve cell function and survival. In this perspective, we hypothesize that the availability of glucose is central to the core mechanism of photobiomodulation; that photobiomodulation is at its most efficient in stimulating mitochondrial activity and improving cell function when there is glucose readily available.