Fluorescence-based saccharide sensing using boronic acid-based entities has been investigated for nearly 25 years because it is recognized that boronic acids have the potential to afford semi-invasive or non-invasive monitoring of carbohydrate levels in a variety of medical conditions, including cancer and diabetes. Glucose-level monitoring is of paramount importance to limit the long-term consequences of diabetes mellitus (e.g. damage to the heart, eyes, kidneys, nerves and other organs caused by malign glycation of vital protein structures). A number of challenges still require improvement, including increased discrimination between monosaccharides, functioning under physiological conditions and sensor stability towards photobleaching or oxidation. The relative binding constants (K) of monosaccharides with boronic acids reveal glucose to be a weak boronic acid binder, and D-fructose a strong binder which presents a problem in the development of glucose-selective artificial receptors. This issue has been partially ameliorated by the utilization of diboronates. However, these bulkier sensors tend to be less water soluble than their monoboronate counterparts. Increasing the sensor’s water solubility profile, whilst still retaining the low pKa values for binding at neutral pH, has been achieved by introduction of a pyridiniumboronic acid unit in the sensor molecule.