A potential link between magnesium intake and diabetes in Indigenous Australians

To the Editor: Diabetes in Indigenous Australians occurs at a younger age and at almost four times the rate in non-Indigenous Australians. The age-adjusted prevalence of diabetes among Indigenous people is 16% in remote areas and 9% in non-remote areas, with the actual prevalence estimated to be between 20% and 25%, and possibly higher than 30% in some remote areas.1 The cause for this disparity in diabetes incidence is multifactorial, and recent evidence suggests that nutrition — particularly magnesium intake — may play a role.

Although central obesity remains a major risk factor, magnesium deficit has been posited to be an underlying common mechanism for the insulin resistance found in type 2 diabetes, as well as in metabolic syndrome, hypertension, and impaired glucose tolerance.2 The clinical correlations between low magnesium and diabetes have been well documented,3 with serum magnesium deficits being reported in 25%–39% of diabetic outpatients in the United States and Switzerland, and up to 73% of diabetic outpatients in Mexico.

With magnesium deficits being observed in diabetes, studies examining the effects of magnesium-rich foods on diabetes risk become relevant. The Nurses’ Health Study and the Health Professionals’ Follow-up Study, which included 85 060 women (18 years follow-up) and 42 872 men (12 years follow-up), demonstrated that, after adjusting for confounding variables, a magnesium-rich diet reduced the relative risk of developing diabetes by 34% in women and 33% in men.4 A similar inverse correlation between magnesium intake and diabetes risk was shown in the Iowa Women’s Health Study with a cohort of 35 988 older women,5 and in the Honolulu Heart Program and the Women’s Health Study with cohorts of 8006 men and 39 345 women, respectively.6,7

Despite this growing body of evidence supporting the involvement of magnesium in diabetes, consideration of magnesium status has not been integrated into Australian medical care for diabetes, and more specifically, for Indigenous Australians. It is known that the traditional diet of hunter-gathers such as Indigenous Australians was much more nutrient- and magnesium-rich than the current estimated Australian intake.8 Nonetheless, there remains a lack of information about current magnesium status, including dietary intake, in Indigenous Australians.

It is possible that dietary magnesium intake may be too low to maintain normal serum magnesium homoeostasis, and that this might contribute to the development of type 2 diabetes. Further research into this issue may provide this information.