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Low Magnesium Intake May be Associated with Increased Risk for Type 2 Diabetes

Low dietary magnesium intake may be associated with an increased risk for type 2 diabetes, according to a recent American study.

Magnesium, an important micronutrient found in many unprocessed foods, is a necessary cofactor for several enzymes that function in glucose metabolism. Hypomagnesaemia commonly occurs in patients with type 2 diabetes, and short-term metabolic studies have suggested that magnesium supplementation provides a beneficial effect on insulin action and glucose metabolism.

These observations together with additional studies have led to the proposal that magnesium deficiency may represent a risk factor for type 2 diabetes. To test this hypothesis, Ruy Lopez-Ridaura, MD, of Harvard School of Public Health, Boston, Massachusetts, and colleagues evaluated the association between magnesium intake and type 2 diabetes over a long-term period in a large population of health professionals.

Previous analyses from the Harvard group have suggested an inverse relationship between magnesium intake and type 2 diabetes risk. However, the researchers note that these initial studies did not fully control for other confounding factors.

In the present analysis, a food frequency questionnaire was used every 2-4 years to monitor magnesium intake in 85,060 women and 42,872 men for a duration of 18 and 12 years, respectively. In addition, participants were asked if and when they had ever been diagnosed with diabetes at the time of each questionnaire. Data for known diabetes risk factors were also recorded.

Four thousand eighty-four cases of type 2 diabetes were documented in the women and 1,333 in the men during the study period. Statistical analyses revealed a significant inverse association between magnesium intake and risk of type 2 diabetes in both groups. After adjusting for age and energy intake, the relative risk (RR) for diabetes was 0.55 (95% confidence interval [CI], 0.50-0.61] in women and 0.56 [CI, 0.47-0.67] in men.

The association remained significant after adjusting for additional diabetes risk factors, such as BMI, family history, physical activity, smoking status, alcohol consumption, hypertension and hypercholesterolaemia (RR women, 0.66, 0.60-0.73; RR men, 0.67, 0.56-0.80, P < .001 for trend). Adjustment for other dietary minerals did not weaken the association.

The researchers suggest that the study provides strong and consistent evidence for an association between magnesium deficiency and diabetes risk. "This study supports the dietary recommendation to increase consumption of major food sources of magnesium, such as whole grains, nuts, and green leafy vegetables," they conclude.

Diabetes Care 2004 Jan;27:1:134-140. "Magnesium Intake and Risk of Type 2 Diabetes in Men and Women"

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