Magnesium is an essential mineral that serves as an enzyme cofactor for more than 600 reactions in the body, including harnessing energy from carbohydrates. Unfortunately, magnesium (Mg) insufficiency is common in the United States due to the widespread use of demineralized water and soil and the increased consumption of processed foods. Stress, excessive alcohol consumption, gastrointestinal disorders, and certain medications further deplete Mg status. It has been shown that unhealthy Mg status is associated with the incidence of diabetes, a chronic metabolic disorder characterized by dysregulated insulin secretion and function, resulting in hyperglycemia. 

According to epidemiological studies, Mg intake in the U.S. has significantly decreased from 500 mg to a range of 175 mg to 225 mg per day. Individuals who follow a Western‑style diet consume less than 30% to 50% of the Recommended Daily Allowance (RDA) for Mg, which is 320 mg to 420 mg per day for adults. 

Recent studies suggest that Mg may play a role in glucose and insulin metabolism by regulating tyrosine kinase activity on insulin receptors and glucose transporter type 4 (GLUT4). This may be clinically relevant for those with type 2 diabetes or insulin resistance. In a randomized clinical trial (RCT) involving 42 patients with type 2 diabetes, the group that received 250 mg/day of Mg for three months exhibited significantly improved glucose and insulin metabolism markers – hemoglobin A1C (8.32 to 7.96%), insulin levels (15.56 to 12.18 μIU/mL), C-peptide (2.28 to 1.90 ng/mL), and Homeostatic Model Assessment for Insulin Resistance (HOMA‑IR) (6.16 to 4.44). 

Systematic reviews by Morais et al., Simental-Mendía et al., and Li et al. suggest that healthy Mg status can help support healthy glucose and insulin metabolism. A systematic review and meta‑analysis by Veronese et al. investigated the effects of oral Mg on glucose and insulin‑sensitivity parameters in subjects with diabetes or at high risk of diabetes. The patients who were supplemented with various forms of Mg (ranging from 36.5 mg to 637 mg per day) experienced significantly improved fasting plasma glucose levels after a 2‑hour glucose tolerance test and demonstrated improvements in insulin sensitivity markers compared to a placebo. 

Among 1,000 women with polycystic ovary syndrome, those in the higher quartile of serum Mg concentrations had significantly lower fasting glucose, HOMA‑IR, and testosterone status. After adjusting confounding covariates, serum Mg was independently negatively associated with insulin, glucose, HOMA‑IR, and testosterone in these trials, which was positively correlated with the quantitative insulin‑sensitivity check index. 

The richest sources of magnesium are green leafy vegetables, legumes, nuts, seeds, and whole grains. It is important to note that certain types of food processing that remove the nutrient-rich germ and bran layer of grains (refined grains) may substantially lower magnesium content. That said, given the widespread magnesium insufficiency due to agricultural practices and increased consumption of processed foods, magnesium supplementation may be warranted for certain individuals. 

By Danielle Moyer Male, MS, CNS, LDN and Caitlin Higgins, MS, CNS