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Magnesium for Diabetes

Kayla Masso, PharmD Candidate 2014

History -Magnesium has been studied for years as a form of therapy to improve blood sugar control in people with diabetes. A lack of magnesium has been associated with insulin secretion abnormalities and has been associated with diabetes complications. Magnesium deficits and increased urinary magnesium excretion can occur in people with insulin resistance and/or type 2 diabetes.^{1, 2}  The magnesium loss appears to be secondary to higher concentrations of glucose in the kidney that increase urine output.³

Dose:

 Tolerable Upper Intake Levels (ULs) for Supplemental Magnesium⁴ 

Age 19+

Male 350mg

Female 350 mg

Pregnancy 350 mg

Lactation 350 mg

 Safety- No serious side effects were reported in studies where people with diabetes were given magnesium supplements for up to 16 weeks. However, the long-term safety of magnesium supplements for people with diabetes has not been established. Large doses of magnesium in supplements can cause diarrhea, nausea, vomiting and abdominal cramping. Very large doses, more than 5,000 mg/day per day, can be deadly.¹⁰ Symptoms of magnesium toxicity, serum concentrations > 1.74–2.61 mmol/L, can include hypotension, nausea, vomiting, facial flushing, urine retention, ileus, depression, and lethargy, muscle weakness, difficulty breathing, irregular heartbeat, and cardiac arrest.¹¹ The risk of magnesium toxicity increases with impaired renal function or kidney failure with the reduced ability to remove excess magnesium.^{1, 11} 

Potential drug interactions- magnesium may reduce the absorption of medications when taken at the same time including digoxin, tetracycline antibiotics, nitrofurantoin, folate or iron supplements.

Efficacy- Only a few small, short-term clinical trials have examined the potential affects of supplemental magnesium on control of type 2 diabetes and the results are conflicting.⁵

            For example, 128 patients with poorly controlled diabetes in a Brazilian clinical trial received a placebo or a supplement containing either 500 mg/day or 1,000 mg/day magnesium oxide (providing 300 or 600 mg elemental magnesium, respectively).⁶ After 30 days of supplementation, plasma, cellular, and urine magnesium levels increased in participants receiving the larger dose of the supplement, and their glycemic control improved.

            In another small trial in Mexico, participants with type 2 diabetes and hypomagnesemia who received a liquid supplement of magnesium chloride (providing 300 mg/day elemental magnesium) for 16 weeks showed significant reductions in fasting glucose and glycosylated hemoglobin concentrations compared with participants receiving a placebo, and their serum magnesium levels became normal.⁷

             In contrast, neither a supplement of magnesium aspartate (providing 369 mg/day elemental magnesium) nor a placebo taken for 3 months had any effect on glycemic control in 50 patients with type 2 diabetes who were taking insulin.⁸

Conclusion -Oral magnesium supplementation for 4 to 16 weeks may be effective in reducing plasma glucose levels in patients with type 2 diabetes, but the long‐term benefits and safety of it are unclear without further larger randomized control trials.

The American Diabetes Association states that there is insufficient evidence to support the routine use of magnesium to improve glycemic control in people with diabetes. It further notes that there is no clear scientific evidence to state that vitamin and mineral supplementation benefits people with diabetes who do not have underlying nutritional deficiencies.⁹

References to articles on safety and efficacy

1. Chaudhary DP, Sharma R, Bansal DD. Implications of magnesium deficiency in type 2 diabetes: a review. Biol Trace Elem Res 2010;134:119-29.
2. Tosiello L. Hypomagnesemia and diabetes mellitus. A review of clinical implications. Arch Intern Med 1996;156:1143-8.
3. Rude RK. Magnesium. In: Coates PM, Betz JM, Blackman MR, Cragg GM, Levine M, Moss J, White JD, eds. Encyclopedia of Dietary Supplements. 2nd ed. New York, NY: Informa Healthcare; 2010:527-37.
4. Lima MDL, Cruz T, Pousada JC, et al. The effect of magnesium supplementation in increasing doses on the control of type 2 diabetes. Diabetes Care 1998; 21:682-6.
5. Rodriquez-Moran M, Guerrero-Romero F. Oral magnesium supplementation improves insulin sensitivity and metabolic control in type 2 diabetic subjects: a randomized double-blind controlled trial. Diabetes Care 2003; 26:1147-52.
6. de Valk HW, Verkaaik R, van Rijn HJ et al. Oral magnesium supplementation in insulin-requiring Type 2 diabetic patients. Diabet Med 1998; 15:503-7.
7. Evert AB, Boucher JL, Cypress M, et al. Nutrition therapy recommendations for the management of adults with diabetes. Diabetes Care 2013; 36:3821-42.

1. Institute of Medicine (IOM). Food and Nutrition Board. Dietary Reference Intakes: Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: National Academy Press, 1997.
2. Rodriguez-Moran M, Simental Mendia LE, Zambrano G, et al. The role of magnesium in type 2 diabetes: a brief based-clinical review. Magnes Res 2011; 24:156-62.

10.  Kutsal E, Aydemir C, Eldes N, et al. Severe hypermagnesemia as a result of excessive cathartic ingestion in a child without renal failure. Pediatr Emerg Care 2007;23:570-2.

11.  Musso CG. Magnesium metabolism in health and disease. Int Urol Nephrol 2009; 41:357-62.m