Serum and Dietary Magnesium and the Risk for Type 2 Diabetes Mellitus

Abstract

TYPE 2 DIABETES mellitus imposes a substantial public health burden in the United States. It affects approximately 15 million Americans and leads to an excess risk for blindness, renal failure, lower-extremity amputation, and cardiovascular disease.^1,2 The pathogenesis of the disease is complex. To date, only obesity and physical inactivity have been well established as modifiable risk factors for type 2 diabetes.^3,4 Several lines of evidence suggest a possible novel risk factor: magnesium deficiency.^5-8 First, several large observational studies, including the Atherosclerosis Risk in Communities (ARIC) Study, have demonstrated strong cross-sectional associations between low serum magnesium levels and type 2 diabetes.^7,9-14 Second, in vitro studies have shown an effect of magnesium on the secretion of insulin by the pancreas and on the responsiveness to insulin by peripheral tissues.^15,16 Third, magnesium supplementation prevents the development of diabetes in a rat model of spontaneous type 2 diabetes.¹⁷ Finally, clinical intervention studies demonstrated that daily magnesium supplementation can improve short-term insulin response and glucose handling in diabetic individuals.^18-22 The establishment of an association between serum magnesium level and the risk for diabetes might suggest dietary or pharmacological measures to prevent type 2 diabetes. To our knowledge, the association of magnesium intake or magnesium body content, as reflected by serum magnesium level, with type 2 diabetes has only been studied cross-sectionally in humans. We therefore conducted a prospective cohort study to examine the association between serum magnesium level and dietary magnesium intake and the subsequent risk for incident type 2 diabetes in a community-based cohort of middle-aged adults. Cross-sectional analyses were also performed for contrast with the prospective analyses. In light of national survey data indicating that black individuals have lower levels of serum magnesium and are more likely to have type 2 diabetes compared with white individuals,²³ we were particularly interested in this relationship in black participants.