A recent study by Brazilian researchers investigated the effectiveness of metformin, a type 2 diabetes treatment, in gestational diabetes prevention.
The World Health Organization (WHO) considers obesity a global public health problem and one of the major epidemics of this millennium. In Brazil the incidence of obesity cases among women has significantly increased in recent decades, from approximately 1.9 million cases in 1975 to 18 million in 2014. The effect of obesity on women in reproductive age is of concern, as maternal obesity during pregnancy is associated with the development of gestational diabetes. Therefore, preventing and controlling obesity in pregnant women may result in gestational diabetes prevention.
Gestational diabetes is common
During gestation, the most common metabolic disease is gestational diabetes, affecting 3–25% of all pregnancies. All pregnant women who have previously not been diagnosed with diabetes undergo screening for gestational diabetes between 24–28 weeks. Those who are diagnosed with gestational diabetes during pregnancy require prenatal care to stabilize their blood glucose levels.
The prevention and control of hyperglycemia during pregnancy has the potential to reduce immediate adverse pregnancy outcomes, childbirth risks, and costs in the public health care system. Therefore, strategies for gestational diabetes prevention in women at risk of developing the disease is a focus for many physicians and researchers.
Current prevention strategies
Prevention strategies include lifestyle changes with a focus of reducing obesity through diet interventions and increasing physical activity. These strategies could also help reduce issues caused by gestational diabetes by helping to control blood glucose levels and reducing blood pressure and body mass index (BMI). However, if patients do not adhere to these strategies, it will not decrease the incidence of gestational diabetes.
Another preventive strategy is the use of medications aimed at controlling hypoglycemia, such as metformin, which has been shown to help control obesity, one of the main causes of gestational diabetes. Previously, using therapeutic interventions such as metformin has been controversial due to the risk of causing birth defects.
In recent years, however, metformin has no longer been considered to be harmful during pregnancy. It has a low incidence of side effects and has been shown to help control blood glucose levels, reduce BMI, as well as reduce levels of total cholesterol. Therefore, combining these prevention strategies of lifestyle changes and metformin potentially offers a safe and effective approach to gestational diabetes prevention.
How effective are these prevention strategies in reducing gestational diabetes?
A recent randomized clinical trial conducted by researchers in Brazil aimed to evaluate the effectiveness of this potential prevention strategy for gestational diabetes. They investigated the effect of metformin on gestational diabetes prevention in obese pregnant women who were attending a public maternity hospital in Joinville, Brazil. Their results were published in the Revista Brasileira De Ginecologia E Obstetricia.
The trial included 164 obese pregnant women who had a BMI equal to or greater than 30 kg/m2, indicating obesity. The researchers divided the participants into either a control group or a metformin group. Participants in the metformin group received two 500 mg doses of metformin daily (one at breakfast and one at dinner). Both groups also received guidance regarding their diet and physical activity. The researchers assessed the participants upon enrollment and again at weeks 24–28 of gestation. They primarily looked at the effects of metformin on BMI and diagnosis of gestational diabetes.
No significant differences between groups
The results showed no significant difference between the control and metformin groups regarding changes observed in BMI. Diagnosis of gestational diabetes was greater in the control group (19.5%) compared to the metformin group (15.9%), indicating the risk of developing gestational diabetes was not significantly reduced (only 3.6%) for patients taking metformin.
This study lacks evidence to offer significant conclusions about the benefits of metformin as the results show metformin did not have a significant impact on reducing the risk of gestational diabetes.
Limitations noted by the researchers in this trial included the small sample size for each group and the effectiveness and adherence to dietary and physical activity interventions.
The authors suggest that further studies with a large number of participants from multiple centers across the country are needed. They also suggest that future studies should include a group without lifestyle interventions to confirm the efficacy of metformin as a strategy for gestational diabetes prevention.
Written by Lacey Hizartzidis, PhD
Reference: Sales WB, Nascimento IBD, Dienstmann G, Souza MLR, Silva GDD, Silva JC. Effectiveness of Metformin in the Prevention of Gestational Diabetes Mellitus in Obese Pregnant Women. Rev Bras Ginecol Obstet. 2018 Apr;40(4):180-187. doi:10.1055/s-0038-1642632. Epub 2018 Apr 27.