Before someone develops type 2 diabetes or Metabolic Syndrome, he or she starts out by becoming intolerant to glucose. Glucose intolerance is an umbrella term for metabolic conditions which result in higher than normal blood glucose levels – hyperglycemia.
There is a connection between magnesium levels and glucose metabolism. One study, published in Clinical Laboratory (2008; 54(5-6): 169-72) looked at magnesium levels in over 7,600 subjects over the age of 35 and found that patients with fasting glucose levels greater than 7 mmol/L were more likely to have low magnesium levels than those with low glucose levels. Another observational study involving 1,223 men and 1,485 women free from diabetes, appearing in the Journal of the American College of Nutrition (2006; 25(6): 486-92), dietary intake of magnesium was found to be inversely associated with fasting insulin, and post-glucose challenge plasma insulin.
A study appearing in the American Journal of Clinical Nutrition (1992;55:1161-1167) found that when compared to controls, a group of subjects getting the equivalent of 360 grams of magnesium per day had higher erythrocyte magnesium levels and better glucose tolerance than controls. Subjects with insulin resistance and low magnesium levels experienced improved glucose handling when given magnesium supplementation. The authors of this study believed that increasing magnesium decreases the chance of developing type 2 diabetes.
Magnesium is an important cofactor for many of the enzymes involved with carbohydrate metabolism. It is necessary for the phosphoylation of glucose and is important for the function of the citric acid cycle. Magnesium affects both insulin secretion and action, so it is important for blood sugar control. Low levels of magnesium are also related to some of the complications of diabetes, like retinopathy and heart disease. It is important for the function of over 300 enzymes, including enzymes for energy transfer and utilization. Adequate magnesium is necessary for the release of insulin. Animal studies have shown that severe magnesium deficiency can result in the loss of pancreatic beta cells. A study appearing in Clinical Pharmacology and Therapeutics (1991;49:39-43) showed that magnesium supplementation improved the efficacy of glipizide. Articles appearing in Diabetolgia (1990;33:501-514) and Diabetes Research and Clinical Practice (1990;10:203-209) go into great detail of the importance of magnesium in glucose metabolism.