Magnesium Supplementation Lowers Blood Sugar in Older Adults

A recent study published in the journal Frontiers in Nutrition has found that magnesium supplementation can lower fasting blood glucose levels in older adults suffering from magnesium deficiency. The research highlights the potential benefits of magnesium for managing prediabetes, although experts caution that more comprehensive interventions may be necessary to effectively halt the progression to type 2 diabetes.

Prediabetes is characterized by elevated blood glucose levels that have not yet reached the threshold for diabetes. It represents a critical opportunity for intervention, as untreated prediabetes can lead to serious health consequences. The study aimed to explore whether magnesium supplementation could improve glycemic control in older adults with hypomagnesemia, a condition where magnesium levels are below normal.

Study Design and Findings

The research involved a randomized controlled trial that spanned 16 weeks and included 71 older Chinese adults with prediabetes and magnesium deficiency. Participants were assigned to receive either 360 mg of magnesium oxide daily or a placebo. Of the original participants, 65 completed the trial.

The primary objective was to evaluate changes in fasting plasma glucose (FPG) levels from baseline to the fourth month of the study. In addition to FPG, researchers assessed insulin levels, C-peptide, and insulin resistance using the homeostasis model assessment of insulin resistance (HOMA-IR). They also measured glycated hemoglobin (HbA1c) and various inflammatory markers.

The results indicated that magnesium supplementation significantly increased serum magnesium levels compared to the placebo group, with an adjusted mean difference of 0.056 mmol/L. Participants receiving magnesium also experienced a modest reduction in fasting glucose, with an adjusted mean difference of -0.5 mmol/L.

Despite these positive outcomes, other glycemic measures, including HbA1c, did not show significant changes, suggesting that the reduction in fasting glucose may not reflect broader improvements in overall glycemic control.

Implications and Limitations

The authors of the study emphasize that magnesium supplementation appears to enhance glucose metabolism primarily in individuals with hypomagnesemia. Notably, adherence to the intervention protocol was high, as nearly 92% of participants reported following the guidelines. Furthermore, the intervention was well tolerated, with no adverse events linked to magnesium supplementation.

Despite its strengths, the study has limitations that affect the interpretation of its findings. The sample size was relatively small, which may limit the generalizability of the results. Additionally, relying solely on fasting glucose as a metric may overlook other important markers of glucose metabolism.

The relatively low bioavailability of magnesium oxide compared to other formulations, such as magnesium citrate or glycinate, may also have constrained the physiological impact of the supplementation. Future research is needed to evaluate different magnesium formulations and establish a dose-response relationship.

Overall, while the study demonstrates that magnesium supplementation can increase serum magnesium levels and reduce fasting glucose concentrations in older adults with magnesium deficiency, the evidence for a comprehensive improvement in glucose metabolism is limited. Larger trials with extended follow-up periods are necessary to clarify the clinical significance of these findings and to explore the potential of magnesium as a preventive measure against diabetes progression.

The study was authored by Yang, J., and colleagues, and is available in Frontiers in Nutrition. For further reading, the full article can be accessed at https://doi.org/10.3389/fnut.2026.1765308.