Magnesium and diabetes : it’s implications for the health of indigenous Australians.

Abstract

Diabetes in Indigenous Australians occurs at a younger age and at almost four times the rate of non-Indigenous Australians. While the cause for this health disparity is multi-factorial, recent studies suggest that nutrition, and particularly magnesium intake, may play a role in onset of diabetes and related pathologies. No study has ever examined whether there is any relationship between diabetes and magnesium intake in Indigenous Australians, and the present study therefore sought to establish whether any such interrelationship existed. As part of this study, dietary magnesium intake was estimated in an urban cohort of Aboriginal and Torres Strait Islander subjects and compared to the average Australian dietary intake. An ecological study then explored environmental correlates, and specifically the magnesium level in drinking water, to diabetes mortality. Finally, total and free serum magnesium concentrations were determined to identify any differences in magnesium status between diabetic and non-diabetic Indigenous and non-Indigenous Australians, and also to compare which of the two parameters was a more sensitive measure of magnesium status and diabetic risk. All Aboriginal and Torres Strait Islander people that were recruited for this study were patients of the Townsville Aboriginal and Islander Health Services, Townsville, North Queensland, who presented for health monitoring and subsequently required fasting blood tests as part of that routine care. Additional non-Indigenous people were recruited from five GP practices in the Townsville area. Inclusion criteria included persons over the age of 15 (Tanner Stage 5) who had lived in the Townsville area for at least ten days. Exclusion criteria included chronic diarrhoea, alcoholism or binge drinking in the past two weeks, use of diuretics, consumption of magnesium supplements, reduced renal function (urinary albumin to creatinine ratio exceeding > 2.5 mg/mmol in men and > 3.5 mg/mmol in women), severe mental illness, pregnancy, or breastfeeding. Our results indicated that 60% of the Indigenous people assessed in this study had a dietary intake of magnesium that was below the estimated average magnesium requirement for half the national population. Additionally, the average magnesium intake in Indigenous Australians was significantly less than the intake of non-Indigenous Australians (p<0 .001). A significant negative correlation was found between the incidence of diabetes related mortality and the concentration of magnesium in drinking water in Queensland, confirming previous reports from the USA that drinking water magnesium may be an important factor in development of diabetes. The needs assessment study confirmed that diabetes in both Indigenous and non-Indigenous Australians was associated with reduced levels of total serum magnesium, and more importantly, that total serum magnesium was lower in Indigenous Australians who did not have diabetes compared with their non-Indigenous counterparts (p=<0.001). In the absence of diabetes, the prevalence of hypomagnesaemia was 17.2% for the non-Indigenous but 36.9% for the Indigenous subjects. Finally, the ionic serum magnesium analysis confirmed the results of the total serum magnesium study, and demonstrated that ionic magnesium was strongly correlated to the total magnesium concentration (r: 0.75. p < 0.001), with the relationship being apparent irrespective of either diabetic (r: 0.66 to 0.81. p<0.001) or ethnicity (r = 0.71 to 0.81. p<0.001)." We conclude that although not causal, the evidence suggests that magnesium may be a significant contributing factor to diabetes in Australia, especially for Aboriginal and Torres Strait Islander peoples, and that further investigation of the potential relationship between magnesium and diabetes in the Australian Indigenous populations, and possible corrective interventions, is highly warranted.