Aims: Magnesium is a cofactor for numerous metabolic enzymatic reactions. It is required for glucose utilization and insulin signaling. We compared plasma magnesium concentrations in pregnant women with and without abdominal obesity, and investigated the interactive roles of magnesium and obesity in the development of gestational diabetes mellitus (GDM).
Methods: Pregnant women with and without abdominal obesity (n = 40 in each group) were followed during gestation. Oral glucose tolerance tests (OGTT) were performed at 24-28 weeks of pregnancy to diagnose GDM. Plasma glucose, insulin, triglycerides, high-sensitive C-reactive protein (hs-CRP), and malondialdehyde (MDA) were measured. The obesity-GDM relationship was investigated prospectively, and the magnesium-GDM relationship was analyzed on a cross-sectional basis.
Results: Sixteen patients in the obese group and one in the control developed GDM. There were no differences in plasma magnesium levels between obese and control groups (p-value = 0.14), but significant differences between diabetic and non-diabetic patients (p-value = 0.05). Fourteen out of 17 diabetic patients had magnesium concentrations below the median. Increases in insulin, homeostatic model for insulin resistance, triglycerides, hs-CRP, MDA and second-hour blood glucose were more pronounced in those with both abdominal obesity and low-normal magnesium concentrations. In the Poisson regression model, obesity (relative risk = 20.6, p-value = 0.002), low-normal magnesium level (relative risk = 4.2, p-value = 0.009), and their interaction (p-value<0.001) were significant.
Conclusion: Abdominally obese patients with lower plasma magnesium are more likely to show abnormal OGTT results. Insulin resistance, inflammatory response and oxidative stress are exaggerated in these patients.
Keywords: abdominal obesity; gestational diabetes mellitus; inflammation; magnesium; oxidative stress.