Magnesium Deficiency Disrupts Blood Glucose Homeostasis in a Time-of-Day-Dependent Manner

Magnesium deficiency (MgD) disrupts numerous physiological processes, yet its specific impact on in vivo glucose homeostasis remains unclear. This study investigated the longitudinal effects of MgD on blood glucose dynamics in freely moving rats using continuous glucose monitoring. Animals were maintained on a 2–3-week MgD or Control diet under two conditions: access to standard drinking water or a 10% glucose solution. Under standard drinking water conditions, MgD rats exhibited significantly lower mean blood glucose levels specifically during the quiescent day phase, although nonlinear fluctuation patterns remained comparable to those of controls. Conversely, when provided with the glucose solution, MgD rats increased fluid intake, exhibiting a behavioral compensation that normalized mean glucose levels despite the hypoglycemic tendency. However, detailed time-series analysis utilizing recurrence plots revealed that this compensation coincided with altered dynamics; MgD rats exhibited significant impairment in the periodicity of glucose fluctuations during the day phase under the glucose-challenge condition, indicating disrupted blood glucose homeostasis. These findings suggest that chronic MgD lowers baseline glucose levels, potentially via enhanced insulin secretion, thereby further compromising glucose stability under metabolic challenge. This study highlights the important role of magnesium (Mg) in maintaining circadian glucose rhythmicity and pancreatic functional integrity. Consequently, we propose the synergistic application of Mg assays and continuous glucose monitoring as biomarkers for metabolic disorders.