Lower serum magnesium concentration is associated with diabetes, insulin resistance, and obesity in South Asian and white Canadian women but not men

Abstract

Background: A large proportion of adults in North America are not meeting recommended intakes for magnesium (Mg). Women and people of South Asian race may be at higher risk for Mg deficiency because of lower Mg intakes relative to requirements and increased susceptibility to diabetes, respectively.

Objective: This study compared serum Mg concentrations in South Asian (n=276) and white (n=315) Canadian women and men aged 20-79 years living in Canada's Capital Region and examined the relationship with diabetes, glucose control, insulin resistance, and body mass index.

Results: Serum Mg concentration was lower in women of both races and South Asians of both genders. Racial differences in serum Mg were not significant after controlling for use of diabetes medication. A substantial proportion of South Asian (18%) and white (9%) women had serum Mg <0.75 mmol/L indicating hypomagnesemia. Use of diabetes medication and indicators of poorer glucose control, insulin resistance, and obesity were associated with lower serum Mg in women, but not in men.

Conclusions: These results suggest that the higher incidence of diabetes in South Asians increases their risk for Mg deficiency and that health conditions that increase Mg requirements have a greater effect on Mg status in women than men.

Keywords: McAuley's index; adults; body mass index; glucose; homeostatic model assessment of insulin resistance; magnesium status; quantitative insulin sensitivity check index.

Fig. 1

Serum Mg concentrations of participants. Bars represent the means±SEM. Numbers above the bars in parentheses indicate the number of participants in that group. Bars without a common letter differ, p<0.05. SM, South Asian men; SW, South Asian women; WM, white men; WW, white women.

Fig. 2

Classification of participants according to serum Mg concentrations. Bars represent the percentages of participants with hypomagnesemia (<0.75 mmol/L), chronic latent Mg deficiency (0.75 –<0.85 mmol/L), or normal serum Mg (≥0.85 mmol/L). Numbers above the bars in parentheses indicate the number of participants in that group. Bars without a common letter within each category differ, p<0.05. SM, South Asian men; SW, South Asian women; WM, white men; WW, white women.

Fig. 3

Fasting serum glucose (a), fasting plasma insulin (b), QUICKI (c), HOMA-IR (d), and McAuley's index (e) of participants categorized as having hypomagnesemia (<0.75 mmol/L), chronic latent Mg deficiency (0.75 –<0.85 mmol/L), or normal serum Mg (≥0.85 mmol/L). Bars represent the means±SEM. Number of participants in each group in panels (a–e) are the same as shown in Fig. 2. Bars without a common letter for each group of participants differ, p<0.05. SM, South Asian men; SW, South Asian women; WM, white men; WW, white women.

Fig. 4

Serum Mg concentrations of participants categorized as having normal (white bars) or abnormal (black bars) values for fasting serum glucose (a), fasting plasma insulin (b), QUICKI (c), HOMA-IR (d) and McAuley's index (e) based on cut-off values for impaired glucose control and insulin resistance. Bars represent the means±SEM. Numbers above the bars in parentheses indicate the number of participants in that group. *Different from participants with normal values, p<0.05. SM, South Asian men; SW, South Asian women; WM, white men; WW, white women.

Fig. 5

Serum Mg concentrations of women and men with a BMI <25 (normal weight), ≥25 –<30 (overweight), or ≥30 (obese) (a). Bars represent the means±SEM. Percentages of women and men with hypomagnesemia according to BMI categories (b). Numbers above the bars in parentheses indicate the number of participants in that group. Bars without a common letter differ, p<0.05.