The influence of exchangeable alkali cations on glucose uptake, interlayer reorganization and ionic transport was investigated in homoionic Wyoming montmorillonite exchanged with the complete alkali series (Li+, Na+, K+, Rb+ and Cs+). Glucose adsorption was rapid during the initial stage and reached equilibrium after ∼6 h. Under the investigated conditions, the equilibrium uptake was highest for the Li- and Cs-exchanged forms, whereas the Na-exchanged form showed the lowest adsorption amount. X-ray diffraction, differential thermal analysis and Fourier-transform infrared spectroscopy collectively support partial accommodation of glucose within the interlayer region without major disruption of the aluminosilicate framework, although the magnitude of the structural response depended strongly on the exchangeable cation. The largest basal expansion was observed for the Li- and Na-exchanged forms, showing that interlayer opening does not directly parallel adsorption capacity across the alkali series. Broadband impedance spectroscopy further indicates thermally activated ionic transport and a marked cation dependence of both direct current (DC) conductivity and activation energy after glucose loading. In particular, glucose adsorption altered the conduction environment more strongly in the Li- and Na-exchanged systems than in the K-, Rb- and Cs-exchanged forms under the same thermal conditioning. Taken together, the results suggest that glucose uptake, interlayer expansion and ionic transport are governed by coupled effects involving cation hydration, interlayer accessibility and local structural organization rather than by a single cation property alone. This comparative dataset provides a basis for understanding how exchangeable cations regulate saccharide–clay interactions in montmorillonite.