Abstract & Commentary
Synopsis: Plasma fasting insulin levels are higher and the risk for developing type 2 diabetes is greatest in those with the lowest intake of magnesium (Mg).
Sources: Song Y, et al. Diabetes Care. 2004;27:59-65;Lopez-Ridaura R, et al. Diabetes Care. 2004;27:134-140.
The report by Song and colleagues used a validated food frequency questionnaire in 39,345 women from the Women's Health Study. The relative risks of type 2 diabetes occurring across quintiles of Mg intake were determined over a 6-year period. There was a significant inverse relationship between Mg intake from both food and supplements, and the development of type 2 diabetes. Although there was a trend (P = 0.05) between Mg intake and the occurrence of diabetes in those women with a Body Mass Index (BMI) of less than 25 kg/m2 there was a significant increase in the relationship in those women with a BMI of 25 kg/m2 or greater.
In a sample of 349 subjects from this study they measured fasting plasma insulin levels to examine their relationship to Mg intake. The mean insulin levels for overweight women in the lowest quintile was 53.5 compared to 41.5 pmol/L among those at the highest quintile.
The report of Lopez-Ridaura and colleagues followed 85,060 women and 42,872 men. Mg intake was evaluated using a validated food frequency questionnaire every 2-4 years. The follow up period in women was 18 years and 12 years in men. After adjusting for family history, age, BMI, physical activity, smoking, alcohol consumption, hypertension, and hypercholesterolemia the relative risk for type 2 diabetes was 0.67 (P < 0.001) in men and 0.66 for women (P < .001) comparing the highest and lowest quintile of total Mg intake.
These findings suggest a significant inverse association between Mg intake and diabetes risk. It also supports the recommendation to increase consumption of major food sources of magnesium such as whole grains, nuts, and green leafy vegetables.
Comment by Ralph R. Hall MD, FACP
Nadler1 in an accompanying editorial reviewed previous reports from the Iowa Women's Health Study2 and the Honolulu Heart Program3 in which increased intake of Mg and whole grains reduced the incidence of cardiovascular disease as well as diabetes. There is sufficient evidence to support a trial of diets such as whole grains nuts, and leafy green vegetables in patients at risk for type 2 diabetes. This diet is consistent with current dietary recommendation for the prevention of cardiovascular disease as well. The benefits of lifestyles with appropriate exercise and nutrition are tremendous in terms of morbidity, quality of life, and financial gain. It seems so simple—why can’t we do more?
Dr. Hall, Emeritus Professor of Medicine University of Missouri- Kansas City School of Medicine, is Associate Editor of Internal Medicine Alert.
1. Nadler JA, et al. Diabetes Care. 2004;27:270-271.
2. Meyer KA, et al. Am J Clin Nutr. 2000:71;921-930.
3. Abbott RD, et al. Am J Cardiol. 2003;92:665-669.