People with diabetes are constantly being inundated with news about new supplements that supposedly they should be taking to improve blood sugar control and prevent complications, including chromium, vitamin D, alpha-lipoic acid, vinegar, cinnamon, and more….
Athletes (whether they have diabetes or not) are bombarded with the same sorts of marketing from supplement companies, but they are often falsely promised the means to speed up their recovery, boost their power, increase their endurance, and prevent muscle cramps (to name a few).
One supplement in particular has been examined for use in both diabetes and athletic endeavors: magnesium. It is a mineral that exists in the human body in abundance and is involved in numerous processes that affect muscle function, including oxygen uptake, energy production, and electrolyte balance. Some evidence suggests that marginal magnesium deficiency impairs exercise performance and amplifies the negative aspects of strenuous exercise (e.g., oxidative stress). Strenuous exercise apparently increases urinary and sweat losses of magnesium that may increase daily intake requirements by 10 to 20 percent. Based on dietary surveys and recent human experiments, a magnesium intake of less than 260 mg/day for male and 220 mg/day for female athletes may result in a magnesium-deficient status, which may apply to a number of athletes, particularly those participating in sports requiring weight control like wrestling and gymnastics that make them more likely to have inadequate magnesium intake (1).
Magnesium studies in athletes — whether they are involved in strength, power, or aerobic events — have shown equivocal results (1). Supplements taken by deficient athletes do benefit exercise performance, but (not surprisingly) provide nothing to active individuals who already have enough (2); trained subjects appear to benefit less than untrained subjects (2). Little research has focused on physically active females who may be at the highest risk for magnesium deficiency, and studies have been confounded by numerous factors including poor study design and concomitant use of other supplements. Magnesium supplementation does appear to increase the training athlete’s erythrocyte and hemoglobin levels, though (3).
It has been estimated that ~60 percent of American adults fail to consume the estimated average requirement for magnesium. Aside from having a negative impact on the energy production pathway required by mitochondria to generate ATP, magnesium deficiency also reduces your antioxidant capacity as you age and your resistance to free-radical damage, given that it protects against free radical damage of mitochondria. A low magnesium status has been associated with numerous pathological conditions characterized by chronic inflammatory stress. Aging itself is very often associated with magnesium deficiency (usually caused by dietary deficiency) and with increased incidence of many chronic diseases, muscle loss and sarcopenia, altered immune responses, and vascular and metabolic conditions (4).
To this point, we have mainly talked about athletes and aging, so where does diabetes come into this discussion? Data from NHANES 99-02 found that deficiencies of chromium, copper, iron, and magnesium increase adiposity (5). Most people with type 2 diabetes are overweight or obese, conditions that are usually characterized by chronic low-grade inflammation and increased incidence of a low magnesium status. Chronic inflammation and oxidative stress related to marginal-to-moderate magnesium deficiency, therefore, may be contributing significantly to the occurrence of obesity and chronic diseases like atherosclerosis, hypertension, osteoporosis, cancer, and diabetes mellitus (6).
How does magnesium directly impact diabetes control and risk? Magnesium is known to modulate insulin-mediated glucose uptake, and even in individuals without diabetes, hypomagnesemia is associated with a decrease in the 1st and 2nd phases of insulin secretion (i.e., a lesser overall insulin secretion) (7). In another recent study, fasting glucose levels in individuals with type 2 diabetes were related to urine, plasma and dietary magnesium, suggesting that this mineral plays an important role in blood glucose control (8). Seventy-seven percent of the diabetic participants in that study presented one or more magnesium status parameters below the cut-off points for urine, plasma, and erythrocytes. Moreover, oral magnesium supplements improve insulin sensitivity even in normomagnesemic, overweight, nondiabetic subjects, emphasizing the need for an early optimization of magnesium status to prevent insulin resistance and type 2 diabetes onset (9).
In conclusion, while much research in this area remains to be conducted, it is likely that making sure that all of your diabetes patients have an adequate dietary intake of magnesium (from food sources and supplements) will benefit their bodies in many ways, including improvement of blood glucose control and prevention of chronic complications (related to oxidative stress). Anecdotally, I have also heard of magnesium supplements reducing the incidence of muscle cramps during and after physical activity and improving blood sugar control in at least one extreme type 1 diabetic athlete, but research in those areas remains limited.
- The effects of magnesium supplementation on exercise performance. Newhouse IJ, Finstad EW. Clin J Sport Med. 2000;10(3):195-200.
- Update on the relationship between magnesium and exercise. Nielsen FH, Lukaski HC. Magnes Res. 2006;19(3):180-9.
- Effects of magnesium supplementation on blood parameters of athletes at rest and after exercise. Cinar V, Nizamlioglu M, Mogulkoc R, Baltaci AK. Biol Trace Elem Res. 2007;115(3):205-12.
- Magnesium and aging. Barbagallo M, Dominguez LJ. Curr Pharm Des. 2010;16(7):832-9.
- An examination of the association of selected toxic metals with total and central obesity indices: NHANES 99-02. Padilla MA, Elobeid M, Ruden DM, Allison DB. Int J Environ Res Public Health. 2010;7(9):3332-47.
- Magnesium, inflammation, and obesity in chronic disease. Nielsen FH. Nutr Rev. 2010;68(6):333-40.
- Insulin secretion is decreased in non-diabetic individuals with hypomagnesemia. Rodríguez-Morán M, Guerrero-Romero F. Diabetes Metab Res Rev. 2011 Apr 12 [Epub ahead of print].
- Influence of magnesium status and magnesium intake on the blood glucose control in patients with type 2 diabetes. Sales CH, Pedrosa LF, Lima JG, Lemos TM, Colli C. Clin Nutr. 2011;30(3):359-64.
- Oral magnesium supplementation reduces insulin resistance in non-diabetic subjects – a double-blind, placebo-controlled, randomized trial. Mooren FC, Krüger K, Völker K, Golf SW, Wadepuhl M, Kraus A. Diabetes Obes Metab. 2011;13(3):281-4.
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