Magnesium chloride supplementation reduces risk of gestational diabetes by improving glucose levels and controlling body weight gain in diet-induced obese, hypomagnesaemic rats: a pilot study

The role of magnesium supplementation in reducing the risk of gestational diabetes (GD) has not been elucidated. To evaluate the effect of magnesium chloride (MgCl2) on the risk of developing GD in a model of obese rats with hydrochlorothiazide-induced hypomagnesemia. Female Wistar rats were allocated into a healthy control or obese group. Obesity was induced with an obesogenic diet and defined by a body weight 30% higher than that of the healthy control group. Once obesity was induced and before pregnancy, hypomagnesemia was generated using hydrochlorothiazide (5 mg/kg body weight). Subsequently, the oestrous cycle was evaluated to proceed for mating. Once pregnancy was confirmed, the obese rats were allocated to an intervention group (IG) or control group (HOCG). Rats in the IG received MgCl2 (50 mg/kg body weight, equivalent to 500 mg per day in humans). Fasting glucose and ionized magnesium levels were determined on days 6, 15, and 20 of pregnancy. An oral glucose tolerance test was performed on day 15 of pregnancy. Rats in the IG had significantly increased ionized magnesium (p=0.009), decreased fasting (p=0.02) and two-hour post-load (p=0.04) glucose levels, and exhibited lower body weight gain than the HOCG (p<0.05). At the end of the study, 75% of the rats in the HOCG, but none in the IG, fulfilled the diagnostic criteria for GD. In obese hypomagnesaemic rats, magnesium supplementation, using MgCl2, reduces fasting and two-hour post-load glucose levels as well as the risk of developing GD, and induces lower body weight gain during pregnancy.