Serum and dietary magnesium and the risk for type 2 diabetes mellitus: the Atherosclerosis Risk in Communities Study.
BACKGROUND
Experimental studies in animals and cross-sectional studies in humans have suggested that low serum magnesium levels might lead to type 2 diabetes; however, this association has not been examined prospectively.


METHODS
We assessed the risk for type 2 diabetes associated with low serum magnesium level and low dietary magnesium intake in a cohort of nondiabetic middle-aged adults (N = 12,128) from the Atherosclerosis Risk in Communities Study during 6 years of follow-up. Fasting serum magnesium level, categorized into 6 levels, and dietary magnesium intake, categorized into quartiles, were measured at the baseline examination. Incident type 2 diabetes was defined by self-report of physician diagnosis, use of diabetic medication, fasting glucose level of at least 7.0 mmol/L (126 mg/dL), or nonfasting glucose level of at least 11.1 mmol/L (200 mg/dL).


RESULTS
Among white participants, a graded inverse relationship between serum magnesium levels and incident type 2 diabetes was observed. From the highest to the lowest serum magnesium levels, there was an approximate 2-fold increase in incidence rate (11.1, 12.2, 13.6, 12.8, 15.8, and 22.8 per 1000 person-years; P = .001). This graded association remained significant after simultaneous adjustment for potential confounders, including diuretic use. Compared with individuals with serum magnesium levels of 0.95 mmol/L (1.90 mEq/L) or greater, the adjusted relative odds of incident type 2 diabetes rose progressively across the following lower magnesium categories: 1.13 (95% CI, 0.79-1.61), 1.20 (95% CI, 0.86-1.68), 1.11 (95% CI, 0.80-1.56), 1.24 (95% CI, 0.86-1.78), and 1.76 (95% CI, 1.18-2.61) (for trend, P = .01). In contrast, little or no association was observed in black participants. No association was detected between dietary magnesium intake and the risk for incident type 2 diabetes in black or white participants.


CONCLUSIONS
Among white participants, low serum magnesium level is a strong, independent predictor of incident type 2 diabetes. That low dietary magnesium intake does not confer risk for type 2 diabetes implies that compartmentalization and renal handling of magnesium may be important in the relationship between low serum magnesium levels and the risk for type 2 diabetes.
Kao
W H
WH
Department of Epidemiology, The Johns Hopkins University School of Hygiene and Public Health, Baltimore, MD, USA.
Folsom
A R
AR
Nieto
F J
FJ
Mo
J P
JP
Watson
R L
RL
Brancati
F L
FL
D000328:Adult; D015415:Biomarkers / Q000097:blood*; D044383:Black People; D001786:Blood Glucose / Q000378:metabolism; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000209:etiology*; D005215:Fasting; D005260:Female; D006801:Humans; D015994:Incidence; D007328:Insulin / Q000097:blood; D008274:Magnesium / Q000008:administration & dosage* / Q000097:blood*; D008275:Magnesium Deficiency / Q000097:blood / Q000150:complications* / Q000208:ethnology*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D044465:White People
D015415:Biomarkers; D001786:Blood Glucose; D007328:Insulin; D008274:Magnesium