Higher magnesium intake associated with reduced risk of metabolic impairment, diabetes

Friday, October 11, 2013. In an article published online on October 2, 2013 in the journal Diabetes Care, Boston researchers report an association between greater magnesium intake and a lower risk of developing diabetes over a 6.9 year average period.

"Several clinical studies of magnesium supplementation in those with and without diabetes indicate that magnesium supplementation can improve glycemic control, insulin sensitivity, and beta-cell function," Nicola M. McKeown of Tufts University and colleagues write. "However, the duration of these clinical studies has been relatively short (no more than 6 months) and most of the observational studies of magnesium intake in relation to insulin homeostasis or metabolism have been cross-sectional. As such, there is a relative dearth of knowledge on the long-term impact of magnesium intake on insulin metabolism."

The study included 2,582 men and women enrolled in the Framingham Heart Study Offspring cohort, a longitudinal study of cardiovascular disease. Between 1991 and 1995, the subjects participated in medical examinations that included oral glucose tolerance testing and dietary assessment, and were followed through 1998 to 2001, when they were re-examined.

Thirty-six percent of the participants were classified as having metabolic impairment, defined as impaired fasting glucose, impaired glucose tolerance, insulin resistance or hyperinsulinemia, at the time of the 1991-1995 examinations. Among those without the condition, 18% developed metabolic impairment by the end of the follow-up period. Those without metabolic impairment whose magnesium intake from food and supplements was among the top one-fifth of participants had a 37% lower risk of becoming impaired over follow-up compared with those whose intake was among the lowest fifth.

In subjects classified as metabolically impaired at baseline, 16.6% became diabetic by the end of follow-up. Having a magnesium intake that was among the highest fifth lowered the risk of developing diabetes in this group by 32% in comparison with an intake that was lowest. When the entire study population was considered, those whose magnesium intake was highest had approximately half the risk of becoming diabetic over follow-up than subjects whose intake was lowest.

"These findings support a role for higher magnesium intake in those at high risk of developing diabetes, and the need for large, randomized trials to confirm these observations," the authors conclude.